@article {pmid39431684,
year = {2024},
author = {Schwaar, N and Benke, D and Retsch, M and Goedel, WA},
title = {Float-Cast Microsieves with Elliptical Pores.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.4c01232},
pmid = {39431684},
issn = {1520-5827},
abstract = {Polymeric microsieves bearing elliptical pores were successfully prepared via float-casting: a dispersion comprising nonvolatile acrylate monomers and ellipsoidal polystyrene particles was spread onto a water surface. The resulting self-organized monolayer was laterally compressed, and the monomer was photopolymerized, giving rise to a membrane comprising ellipsoidal particles laterally embedded in a 0.5 μm thin polymer membrane. The particles were dissolved, leaving behind elliptical pores. These pores had an average length of the major axis of 0.87 ± 0.1 μm and of the minor axis of 0.42 ± 0.07 μm and an aspect ratio of approximately 2. The microsieve bearing these submicrometric elliptical pores was transferred to a hierarchical structure made out of microsieves bearing circular pores of 6 μm diameter on top of a microsieve with 70 μm diameter pores. The resulting hierarchically structured microsieve had a porosity of 0.13. At a pressure difference of typically 10[3] Pa (Reynolds number aprox. 0.002), the volumetric permeance for water was Pe = V˙/A/Δp = 0.5·10[-6] m/s/Pa, the product viscosity·permeance is η·V˙/A/Δp = 0.5·10[-9] m. This value is lower than the corresponding values of microsieves with circular pores of similar diameter produced by the same technique. The beneficial effects of higher permeance per pore caused by the elliptical shape are countered by lower porosity caused by less efficient packing of the ellipsoidal particles.},
}

@article {pmid39426070,
year = {2024},
author = {Xiao, H and Liu, Y and Sun, B and Guo, Y and Wang, M},
title = {Multi-scale modeling of aerosol transport in a mouth-to-truncated bronchial tree system.},
journal = {Computers in biology and medicine},
volume = {183},
number = {},
pages = {109292},
doi = {10.1016/j.compbiomed.2024.109292},
pmid = {39426070},
issn = {1879-0534},
abstract = {Computational fluid particle dynamics (CFPD) is widely employed to predict aerosol transport in a truncated bronchial tree model on account of its capacity to reveal details of flow field and particle movement. However, setting a physiologically consistent boundary condition in the CFPD for the idealized or image-based truncated bronchial tree model is still a challenge. This paper proposes a multi-scale modeling method, which contains an Extend-Bronchial tree-Network (EBN) boundary condition for a mouth-to-truncated bronchi system. The comparison between EBN boundary condition and a commonly used uniform pressure (UP) boundary condition is conducted. Subsequently, EBN method is used to study the nano-micron (100 nm-10 μm) particles transport in the mouth-to-truncated bronchi model at different inhalation volume rates (15, 60, 90 L/min). Results show that EBN method is more physiologically rational and two methods differ in flow distribution in lobes, vortex structure, and particle transport. The maximum difference in flow rate distribution in lobes between two methods is about 20 %, while the maximum relative disparity of particle penetration fraction from lobes and deposition fraction in the TLB is about 93 % and 30 %, respectively. Meanwhile, this paper reveals the variation of deposition fraction and penetration fraction with the changes in particle diameter and inhalation volume. Deposition efficiency, deposition hotspots and deposition mechanism are also analyzed with inlet Stokes number (Stk) and Reynolds number (Re). This research establishes a foundation for the simulation of aerosol transport in a whole respiratory tract and provides references for inhalation drug delivery and air pollutant management.},
}

@article {pmid39418303,
year = {2024},
author = {Ding, L and Sabidussi, LF and Holloway, BC and Hultmark, M and Smits, AJ},
title = {Acceleration is the key to drag reduction in turbulent flow.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {43},
pages = {e2403968121},
doi = {10.1073/pnas.2403968121},
pmid = {39418303},
issn = {1091-6490},
abstract = {A turbulent pipe flow experiment was conducted where the surface of the pipe was oscillated azimuthally over a wide range of frequencies, amplitudes, and Reynolds numbers. The drag was reduced by as much as 35%. Past work has suggested that the drag reduction scales with the velocity amplitude of the motion, its period, and/or the Reynolds number. Here, we find that the key parameter is the acceleration, which greatly simplifies the complexity of the phenomenon. This result is shown to apply to channel flows with spanwise surface oscillation as well. This insight opens potential avenues for reducing fuel consumption by large vehicles and for reducing energy costs in large piping systems.},
}

@article {pmid39418306,
year = {2024},
author = {Coquinot, B and Bocquet, L and Kavokine, N},
title = {Hydroelectric energy conversion of waste flows through hydroelectronic drag.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {43},
pages = {e2411613121},
doi = {10.1073/pnas.2411613121},
pmid = {39418306},
issn = {1091-6490},
support = {101071937//EC | ERC | HORIZON EUROPE European Research Council (ERC)/ ; },
abstract = {Hydraulic energy is a key component of the global energy mix, yet there exists no practical way of harvesting it at small scales, from flows with low Reynolds number. This has triggered a search for alternative hydroelectric conversion methodologies, leading to unconventional proposals based on droplet triboelectricity, water evaporation, osmotic energy, or flow-induced ionic Coulomb drag. Yet, these approaches systematically rely on ions as intermediate charge carriers, limiting the achievable power density. Here, we predict that the kinetic energy of small-scale "waste" flows can be directly and efficiently converted into electricity thanks to the hydroelectronic drag effect, by which an ion-free liquid induces an electronic current in the solid wall along which it flows. This effect originates in the fluctuation-induced coupling between fluid motion and electron transport. We develop a nonequilibrium thermodynamic formalism to assess the efficiency of such hydroelectric energy conversion, dubbed hydronic energy. We find that hydronic energy conversion is analogous to thermoelectricity, with the efficiency being controlled by a dimensionless figure of merit. However, in contrast to its thermoelectric analogue, this figure of merit combines independently tunable parameters of the solid and the liquid, and can thus significantly exceed unity. Our findings suggest strategies for blue energy harvesting without electrochemistry, and for waste flow mitigation in membrane-based filtration processes.},
}

@article {pmid39406736,
year = {2024},
author = {Gao, H and Kaltenbach, S and Koumoutsakos, P},
title = {Generative learning for forecasting the dynamics of high-dimensional complex systems.},
journal = {Nature communications},
volume = {15},
number = {1},
pages = {8904},
pmid = {39406736},
issn = {2041-1723},
abstract = {We introduce generative models for accelerating simulations of high-dimensional systems through learning and evolving their effective dynamics. In the proposed Generative Learning of Effective Dynamics (G-LED), instances of high dimensional data are down sampled to a lower dimensional manifold that is evolved through an auto-regressive attention mechanism. In turn, Bayesian diffusion models, that map this low-dimensional manifold onto its corresponding high-dimensional space, operate on batches of physics correlated, time sequences of data and capture the statistics of the system dynamics. We demonstrate the capabilities and drawbacks of G-LED in simulations of several benchmark systems, including the Kuramoto-Sivashinsky (KS) equation, two-dimensional high Reynolds number flow over a backward-facing step, and simulations of three-dimensional turbulent channel flow. The results demonstrate that generative learning offers new frontiers for the accurate forecasting of the statistical properties of high-dimensional systems at a reduced computational cost.},
}

@article {pmid39398115,
year = {2024},
author = {Kumar, KR and Shaik, AH},
title = {Novel 2D Layered MXene Nanofluids for Enhancing the Convective Heat Transfer Performance of Double-Pipe Heat Exchangers.},
journal = {ACS omega},
volume = {9},
number = {40},
pages = {41758-41775},
pmid = {39398115},
issn = {2470-1343},
abstract = {This paper proposes a new class of novel 2D layered structured materials, such as MXene (MX), for the synthesis of innovative nanofluids as coolants to evaluate the convective heat transfer performance of a double-pipe heat exchanger (DPHE). Convective heat transfer experiments were successfully conducted in lab-scale fabricated DPHE using low-concentration MXene nanofluids by varying the volume concentration of MXene nanoparticles (0.01-0.05 vol %) in different base fluids. The influence of the MXene nanofluids on various convective heat transfer parameters, such as LMTD, Nusselt number, heat transfer coefficient, and heat transfer rate without using any inserts in the DPHE was experimentally investigated. The results of the experiments revealed that the heat transfer coefficient and Nusselt number increase with increasing Reynolds number (Re) and concentration of MXene nanoparticles in the base fluids. Maximum enhancement in heat transfer coefficient (126%) was achieved for methanol-based MXene nanofluids at 0.05 vol %. Moreover, the Nusselt number exhibits a maximum enhancement of ∼50% for methanol- and water-based MXene nanofluids. In contrast, the thermal performance factor was also estimated, and it was observed that water- and methanol- based MXene nanofluids showed higher values than castor oil- and silicone oil-based MXene nanofluids. Finally, the LMTD and heat transfer coefficients were successfully validated using Aspen HYSYS 12.1 software.},
}

@article {pmid39387629,
year = {2024},
author = {Küchler, C and Ibanez Landeta, A and Moláček, J and Bodenschatz, E},
title = {Lagrangian particle tracking at large Reynolds numbers.},
journal = {The Review of scientific instruments},
volume = {95},
number = {10},
pages = {},
doi = {10.1063/5.0211508},
pmid = {39387629},
issn = {1089-7623},
abstract = {In the study of fluid turbulence, the Lagrangian frame of reference represents the most appropriate methodology for investigating transport and mixing. This necessitates the tracking of particles advected by the flow over space and time at high resolution. In the past, the purely spatial counterpart, the Eulerian frame of reference, has been the subject of extensive investigation utilizing hot wire anemometry that employs Taylor's frozen flow hypotheses. Measurements were reported for Taylor scale Reynolds number Rλ > 104 in atmospheric flows, which represent the highest strength of turbulence observed on Earth. The inherent difficulties in accurately tracking particles in turbulent flows have thus far constrained Lagrangian measurements to Taylor scale Reynolds numbers up to approximately Rλ = 103. This study presents the Lagrangian particle tracking setup in the Max Planck Variable Density Turbulence Tunnel (VDTT), where Taylor scale Reynolds numbers between 100 and 6000 can be reached. It provides a comprehensive account of the imaging setup within the pressurized facility, the laser illumination, the particles used, and the particle seeding mechanism employed, as well as a detailed description of the experimental procedure. The suitability of KOBO Cellulobeads D-10 particles as tracers within the VDTT is illustrated. The results demonstrate that there is no significant charge exhibited by the particles and that the impact of their inertia on the results is negligible across a wide range of experimental conditions. Typical data are presented, and the challenges and constraints of the experimental approach are discussed in detail.},
}

@article {pmid39386854,
year = {2024},
author = {Das, P and Mamun, MAH},
title = {Predicting MHD mixed convection in a semicircular cavity with hybrid nanofluids using AI.},
journal = {Heliyon},
volume = {10},
number = {19},
pages = {e38303},
pmid = {39386854},
issn = {2405-8440},
abstract = {This study presents a numerical analysis of magnetohydrodynamic (MHD) mixed convection in a semicircular enclosure containing a rotating inner cylinder and filled with nanofluids and hybrid nanofluids. The investigation explores the effects of Al2O3-TiO2-SWCNT-water hybrid nanofluids with varying nanoparticle compositions, as well as Al2O3-water, TiO2-water, and SWCNT-water nanofluids. The analysis includes the development of an artificial neural network (ANN) model to predict outcomes, achieving 97.34 % accuracy in training and 97.41 % in testing for the average Nusselt number. The study examines the impact of Reynolds number (Re), Richardson number (Ri), Hartmann number (Ha), cylinder rotation speed (Ω), cylinder size, and nanoparticle volume fraction (φ) on heat transfer and fluid flow. Key findings include a 6.98 % increase in heat transfer for SWCNT-water nanofluid from Ri = 1 to Ri = 10, a reduction in heat transfer with higher Hartmann numbers, and a significant 21.12 % enhancement when cylinder speed increases to Ω = 10 compared to a stationary cylinder. Larger cylinder sizes also improve convective heat transfer, with a 66.14 % increase for SWCNT-water nanofluid. Additionally, higher concentrations of SWCNT and Al2O3 in hybrid nanofluids enhance heat transfer performance.},
}

@article {pmid39386260,
year = {2024},
author = {Wessies, SS and Yang, JC},
title = {On the Nusselt number correlations of tandem surrogate firebrands on a flat surface.},
journal = {Fire safety journal},
volume = {148},
number = {},
pages = {},
pmid = {39386260},
issn = {0379-7112},
abstract = {Through the heat-mass transfer analogy, naphthalene sublimation experiments were conducted in a heated-air wind tunnel to study the effects of aspect ratio and dimensionless separation distance on the convective heat transfer coefficients of three tandem naphthalene cylinders. Nusselt number correlations were presented for the individual naphthalene cylinders and the full configuration of three cylinders. In all the cases studied, the Reynolds number had the strongest effect on the Nusselt number followed by the aspect ratio and the dimensionless separation distance. Nusselt numbers were higher for the smaller aspect ratios. For a given Reynolds number and aspect ratio, the Nusselt number increases with the dimensionless separation distance.},
}

@article {pmid39341974,
year = {2024},
author = {Huang, N and Han, S and Zhang, X and Wang, G and Jiang, Y},
title = {Effects of surface roughness and Reynolds number on the solute transport through three-dimensional rough-walled rock fractures under different flow regimes.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {22452},
pmid = {39341974},
issn = {2045-2322},
support = {No. tsqnz20221142//Research Fund for Young Expert of Taishan Scholars Project in Shandong Province/ ; No. 52109132//National Natural Science Foundation of China/ ; No. ZR2019ZD14//Major basic research projects of Natural Science Foundation of Shandong Province/ ; },
abstract = {In this study, the effects of surface roughness and Reynolds number (Re) on fluid flow and solute transport are investigated based on a double rough-walled fracture model that precisely represents the natural geometries of rock fractures. The double rough-walled fracture model is composed of two three-dimensional(3D) self-affine fracture surfaces generated using the improved successive random additions (SRA). Simulation of fluid flow and solute transport through the models were conducted by directly solving the Navier-Stokes equation and advection-diffusion equation (ADE), respectively. The results indicate that as the Re increases from 0.1 to 200, the flow regime changes from linear flow to nonlinear flow accompanied with the tortuous streamlines and significant eddies. Those eddies lead to the temporary stagnant zones that delay the solute migration. The increment of Re enhances the transport heterogeneity with the transport mode changing from the diffusion-dominated to the advection-dominated behavior, which is more significant in the fracture with a larger joint roughness coefficient (JRC). All breakthrough curves (BTCs) of rough-walled fractures exhibited typical non-Fickian transport characteristics with "early arrival" and "long tailing" of BTCs. Increasing the JRC and/or Re will enhances the non-Fickian transport characteristics. The ADE model is able to accurately fit the numerical BTCs and residence time distributions (RTDs) at a low Re, but fails to capture the non-Fickian transport characteristics at a large Re. In contrast, the continuous time random walk (CTRW) model provides a better fit to the numerical simulation results over the whole range of Re. Whereas, the fitting error gradually increases with increasing Re.},
}

@article {pmid39329783,
year = {2024},
author = {Li, T and Yang, C and Shao, Z and Chen, Y and Zheng, J and Yang, J and Hu, N},
title = {Fabrication of Patterned Magnetic Particles in Microchannels and Their Application in Micromixers.},
journal = {Biosensors},
volume = {14},
number = {9},
pages = {},
doi = {10.3390/bios14090408},
pmid = {39329783},
issn = {2079-6374},
support = {32071408 and 21827812//National Natural Science Foundation of China/ ; },
mesh = {*Lab-On-A-Chip Devices ; Microfluidic Analytical Techniques ; Microfluidics ; Dimethylpolysiloxanes/chemistry ; Magnetics ; },
abstract = {Due to the extremely low Reynolds number, the mixing of substances in laminar flow within microfluidic channels primarily relies on slow intermolecular diffusion, whereas various rapid reaction and detection requirements in lab-on-a-chip applications often necessitate the efficient mixing of fluids within short distances. This paper presents a magnetic pillar-shaped particle fabrication device capable of producing particles with planar shapes, which are then utilized to achieve the rapid mixing of multiple fluids within microchannels. During the particle fabrication process, a degassed PDMS chip provides self-priming capabilities, drawing in a UV-curable adhesive-containing magnetic powder and distributing it into distinct microwell structures. Subsequently, an external magnetic field is applied, and the chip is exposed to UV light, enabling the mass production of particles with specific magnetic properties through photo-curing. Without the need for external pumping, this chip-based device can fabricate hundreds of magnetic particles in less than 10 min. In contrast to most particle fabrication methods, the degassed PDMS approach enables self-priming and precise dispensing, allowing for precise control over particle shape and size. The fabricated dual-layer magnetic particles, featuring fan-shaped blades and disk-like structures, are placed within micromixing channels. By manipulating the magnetic field, the particles are driven into motion, altering the flow patterns to achieve fluid mixing. Under conditions where the Reynolds number in the chip ranges from 0.1 to 0.9, the mixing index for substances in aqueous solutions exceeds 0.9. In addition, experimental analyses of mixing efficiency for fluids with different viscosities, including 25 wt% and 50 wt% glycerol, reveal mixing indices exceeding 0.85, demonstrating the broad applicability of micromixers based on the rapid rotation of magnetic particles.},
}

*Lab-On-A-Chip Devices
Microfluidic Analytical Techniques
Microfluidics
Dimethylpolysiloxanes/chemistry
Magnetics

@article {pmid39329575,
year = {2024},
author = {Moscato, G and Romano, GP},
title = {Biomimetic Wings for Micro Air Vehicles.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {9},
pages = {},
doi = {10.3390/biomimetics9090553},
pmid = {39329575},
issn = {2313-7673},
abstract = {In this work, micro air vehicles (MAVs) equipped with bio-inspired wings are investigated experimentally in wind tunnel. The starting point is that insects such as dragonflies, butterflies and locusts have wings with rigid tubular elements (corrugation) connected by flexible parts (profiling). So far, it is important to understand the specific aerodynamic effects of corrugation and profiling as applied to conventional wings for the optimization of low-Reynolds-number aerodynamics. The present study, in comparison to previous investigations on the topic, considers whole MAVs rather than isolated wings. A planform with a low aperture-to-chord ratio is employed in order to investigate the interaction between large tip vortices and the flow over the wing surface at large angles of incidence. Comparisons are made by measuring global aerodynamic loads using force balance, specifically drag and lift, and detailed local velocity fields over wing surfaces, by means of particle image velocimetry (PIV). This type of combined global-local investigation allows describing and relating overall MAV performance to detailed high-resolution flow fields. The results indicate that the combination of wing corrugation and profiling gives effective enhancements in performance, around 50%, in comparison to the classical flat-plate configuration. These results are particularly relevant in the framework of low-aspect-ratio MAVs, undergoing beneficial interactions between tip vortices and large-scale separation.},
}

@article {pmid39323288,
year = {2024},
author = {Carrazco-Escalante, M and Hernández-Calderón, Ó and Ríos-Iribe, E and Alarid-García, C and Iribe-Salazar, R and Vázquez-López, Y and Caro-Hernández, O and Pacheco-Plata, F and Caro-Corrales, J},
title = {Heat transfer and friction factor analysis for tomato puree flowing in a concentric-tube heat exchanger.},
journal = {Journal of food science},
volume = {},
number = {},
pages = {},
doi = {10.1111/1750-3841.17396},
pmid = {39323288},
issn = {1750-3841},
abstract = {The heat and momentum transfer of tomato puree through a concentric-tube heat exchanger over a range of generalized Reynolds number (0.05 < Re < 66.5) was experimentally and numerically analyzed. Thermophysical and rheological properties of tomato puree (12°Brix) were measured from 20 to 60°C. The velocity, pressure, and temperature were calculated using the computational fluid dynamics (CFD) software FLUENT[TM] with temperature-dependent transport properties. The thermal operation of the concentric-tube exchanger was satisfactorily predicted using CFD, indicating accurate measurement of tomato puree properties with temperature variations. A concordance was found between the calculated Fanning friction factor and generalized Reynolds with the experimental correlation. A modified Sieder-Tate correlation was established, which allows properly expressing the Nusselt number as a function of the Peclet number. Simple correlations for the mechanical work and the heat transfer rate as a function of the volumetric flow rate were derived. The thermal efficiency was high at low puree flow rates but decreased with higher rates. However, at high flow rates, ceased its decline, instead showing a slight improvement. The analysis confirmed higher heat transfer rates in the concentric-tube heat exchanger compared to a plain tube at low puree flow rates. The results offer valuable insights for assessing diverse operational conditions in dairy, beverage, sauce, and concentrated food industries. Additionally, they also enhance the analysis and design of concentric-tube heat exchangers. PRACTICAL APPLICATION: The knowledge of the rheological and hydrodynamical behavior of fluids in concentric-tube heat exchangers allows to explore a set of different operating conditions to improve the yield and effectiveness on the system heating/cooling design.},
}

@article {pmid39319149,
year = {2024},
author = {Ali, MY and Islam, S and Alim, MA and Biplob, RA and Islam, MZ},
title = {Numerical investigation of MHD mixed convection in an octagonal heat exchanger containing hybrid nanofluid.},
journal = {Heliyon},
volume = {10},
number = {17},
pages = {e37162},
pmid = {39319149},
issn = {2405-8440},
abstract = {Nowadays, the advancement of heat transmission for the heat exchanger device is an important field of research for many researchers. In this work, a numerical study has been conducted to investigate the thermal performance of a mixed convective flow through the octagonal heat exchanger covered by hybrid nanofluid (Cu-TiO2-H2O). A magnetic field has been introduced inside the cavity to investigate the mixed convective hydrodynamics heat flow characteristics. The nanofluid cores absorb/release energy to manage heat transmission by increasing or decreasing inside the cavity domain as the host fluid and dispersed hybrid nanofluid circulate within the cavity. After transforming the governing equations into a generalized, non-dimensional formulation, the finite element approach is utilized to solve the associated equations. Additionally, response surface methodology is also applied to test the responses of the associated factors. Heat transport was examined in relation to the effects of nanofluids fusion temperature, boundary wall properties, Reynolds number, Hartmann number and nanoparticle volume fractions. The outcomes of this study are analysed by measuring streamline profiles, isotherms, average Nusselt number, velocity profile, and 2D and 3D response surfaces of the computational domain. The underlying flow controlling parameters for instance Reynolds number (10 ≤ Re ≤ 200), Hartmann number (0 ≤ Ha ≤100), and nanoparticle volume fractions (0 ≤ ϕ ≤ 0.1), the influences have been considered. The findings also reveal that the thermal performance is being boosted due to augmentation of Re and ϕ, but reverse behavior is noticed for Ha. Furthermore, the response surfaces obtained from response surfaces methodology express that the Re and ϕ have shown positive influence, and Ha has shown negative influence on Nuav. Utilizing a hybrid nanofluid of Cu-TiO2-H2O increases the heat transfer capacity of water to 25.75 %. Moreover, the findings could guide to design of a mixed convective heat exchanger for industrial purposes.},
}

@article {pmid39314537,
year = {2024},
author = {Takyi, J and Beem, HR},
title = {Design & automation of a small-scale towing tank for flow visualization.},
journal = {HardwareX},
volume = {20},
number = {},
pages = {e00585},
pmid = {39314537},
issn = {2468-0672},
abstract = {Although the towing tank is a standard piece of equipment used to investigate fluid phenomena, it primarily exists as custom-built hardware that takes up a significant footprint. The size, cost, and custom-built nature have heretofore inhibited the production of this equipment in the authors' context, an African university. This paper presents a small-scale (1000 mm x 200 mm x 200 mm), low-cost (<$1,000) towing tank made using readily available components and basic digital fabrication tools. Other universities on the continent and beyond can hence create this foundational platform for fluid mechanics-related teaching and research. Leveraging an Arduino microcontroller loaded with the GRBL firmware, G-code is sent from the computer to stepper motors to execute movements in two axes. This allows for automation capabilities, controlled towing speeds, and consistent experimental conditions. Validation tests revealed motion accuracy within 1 %. A glitter-based flow visualization approach to measuring surface phenomena is demonstrated here. Experiments conducted successfully visualized relevant flow characteristics generated by bluff bodies being towed in the tank. As the Reynolds number increased within the operating range, wider wakes and larger, more distinct vortices were generated, as expected. This platform can be replicated widely in institutions that may otherwise forego experimentation in fluid mechanics.},
}

@article {pmid37512786,
year = {2023},
author = {Tahir, MT and Anwar, S and Ahmad, N and Sattar, M and Qazi, UW and Ghafoor, U and Bhutta, MR},
title = {Thermal Management of Microelectronic Devices Using Nanofluid with Metal foam Heat Sink.},
journal = {Micromachines},
volume = {14},
number = {7},
pages = {},
pmid = {37512786},
issn = {2072-666X},
support = {2020R1G1A1012741//National Research Foundation of Korea/ ; },
abstract = {Microelectronic components are used in a variety of applications that range from processing units to smart devices. These components are prone to malfunctions at high temperatures exceeding 373 K in the form of heat dissipation. To resolve this issue, in microelectronic components, a cooling system is required. This issue can be better dealt with by using a combination of metal foam, heat sinks, and nanofluids. This study investigates the effect of using a rectangular-finned heat sink integrated with metal foam between the fins, and different water-based nanofluids as the working fluid for cooling purposes. A 3D numerical model of the metal foam with a BCC-unit cell structure is used. Various parameters are analyzed: temperature, pressure drop, overall heat transfer coefficient, Nusselt number, and flow rate. Fluid flows through the metal foam in a turbulent flow with a Reynold's number ranging from 2100 to 6500. The optimum fin height, thickness, spacing, and base thickness for the heat sink are analyzed, and for the metal foam, the material, porosity, and pore density are investigated. In addition, the volume fraction, nanoparticle material, and flow rate for the nanofluid is obtained. The results showed that the use of metal foam enhanced the thermal performance of the heat sink, and nanofluids provided better thermal management than pure water. For both cases, a higher Nusselt number, overall heat transfer coefficient, and better temperature reduction is achieved. CuO nanofluid and high-porosity low-pore-density metal foam provided the optimum results, namely a base temperature of 314 K, compared to 341 K, with a pressure drop of 130 Pa. A trade-off was achieved between the temperature reduction and pumping power, as higher concentrations of nanofluid provided better thermal management and resulted in a large pressure drop.},
}

@article {pmid36463256,
year = {2022},
author = {Zhu, F and Cheng, J},
title = {Comparison of the effects of litter decomposition process on soil erosion under simulated rainfall.},
journal = {Scientific reports},
volume = {12},
number = {1},
pages = {20929},
pmid = {36463256},
issn = {2045-2322},
mesh = {*Soil Erosion ; Soil ; Forests ; *Pinus ; Plant Leaves ; },
abstract = {Overland flow parameters play a pivotal role in soil erosion, which are affected by litter cover in forests. In this study, the litter layer of Pinus massoniana (Masson pine) was divided into non-decomposed and semi-decomposed layers. Seven litter coverage mass gradients, two slopes (5° and 10°), and two rainfall intensities (60 and 120 mm·h[-1]) were used for a systematic study of the effects of litter layer changes on overland flow dynamic characteristics. The objectives of this study were to explore the soil erosion process in litter different decomposition stages; to explore various relationships between hydraulic variables and litter characteristics. In the process of litter decomposition, overland flow patterns changed from transitional flow to laminar flow and from rapid flow to slow flow. The semi-decomposed layer's Reynold's number (Re), resistance coefficient (f), and soil separation rate ([Formula: see text]) were lower than that of the non-decomposed layer under the same conditions. Litter coverage, runoff and the diameter of the litter were major parameters that affected the Re, f, Fr, and Dr. Shrubs with wide leaves should be selected for understory vegetation replanting. The results of this study are helpful to understand the mechanisms of litter influencing erosion processes in different decomposition stages.},
}

*Soil Erosion
Soil
Forests
*Pinus
Plant Leaves

@article {pmid35853555,
year = {2022},
author = {Kumar, M and Panneerselvam, E and Prabhu, K and Ganesh, SK and Vb, KKR},
title = {Prospective cohort study on short-term evaluation of septoplasty as early management of naso-septal fractures - A correlation of clinical outcomes with computational fluid dynamic parameters.},
journal = {Journal of stomatology, oral and maxillofacial surgery},
volume = {123},
number = {6},
pages = {639-644},
doi = {10.1016/j.jormas.2022.07.010},
pmid = {35853555},
issn = {2468-7855},
mesh = {Humans ; *Nasal Obstruction/diagnosis/etiology/surgery ; Nasal Septum/surgery ; Prospective Studies ; Hydrodynamics ; Pain ; },
abstract = {PURPOSE: Post-traumatic deviated nasal septum (PTDNS) leads to impaired breathing and poor esthetics. The aim of this study was to assess treatment outcomes of early septoplasty for correction of PTDNS and correlate it with computational fluid dynamic (CFD) parameters.

METHODS: This prospective cohort study included patients who underwent early septoplasty for PTDNS. Outcome variables were clinical (pain, nasal symmetry, and nasal obstruction) and computational (velocity, pressure, wall shear stress and Reynold's number). The cohort consisted of two groups: patients with history of closed reduction for nasal fractures (CR) and patients without (NCR). The primary outcome measure was response to treatment. Correlation between clinical and computational parameters, and influence of closed reduction on septoplasty outcomes were the secondary and tertiary outcomes, respectively. Descriptive and inferential statistics were performed to analyze data. Level of significance was fixed at 5% (α = 0.05).

RESULTS: The sample included 12 patients, of which 5 underwent CFD analysis. Pain score reduced from a pre-operative mean of 7.3 to 0.5 post-operatively (p<0.001). All patients demonstrated reduction of nasal obstruction (p<0.001) and deviation (p<0.001) post-operatively. CFD analysis revealed post-operative reduction of velocity (p = 0.005) and Reynold's number (p = 0.007), with positive correlation between nasal obstruction and CFD parameters. Though patients in the CR group demonstrated reduced nasal deviation and obstruction before septoplasty, as compared to the NCR group, their outcomes were comparable following septoplasty.

CONCLUSION: Early septoplasty improves functional and esthetic outcomes in patients with PTDNS. CFD simulation is a predictable method to objectively evaluate nasal function.},
}

Humans
*Nasal Obstruction/diagnosis/etiology/surgery
Nasal Septum/surgery
Prospective Studies
Hydrodynamics
Pain

@article {pmid35672348,
year = {2022},
author = {Saadoon, ZH and Ali, FH and Hamzah, HK and Abed, AM and Hatami, M},
title = {Improving the performance of mini-channel heat sink by using wavy channel and different types of nanofluids.},
journal = {Scientific reports},
volume = {12},
number = {1},
pages = {9402},
pmid = {35672348},
issn = {2045-2322},
abstract = {The combination of nano fluid and changing cross-section mini-channel heat sink effects have become a remarkable choice for the use of thermal devices such as miniature electronic devices to be effectively cooled. In this paper, the comparison of three dimensional straight and wavy channel configuration with using different types nano fluids are numerically investigated. The effects of wave amplitude and A particular type of volume fraction of (Copper Oxide CuO, Dimond Al2O3, Iron Oxide Fe3O4, Titanium Oxide TiO2 and Silver Ag-nano fluids are offered. Three amplitudes of waves (0.15 mm, 0.2 mm and 0.25 mm) and Reynold's number from 200 to 1000 and concentration volume varieties from 0 to 0.075 are used. The effect on thermal resistance, pressures drop, factor of friction of the mini channel is displayed. It is observed that the mini-channel sink's heat transfer efficiency is greatly enhanced compared to the straight channel in an event of adding distilled water as accoolant. The results indicate that nano fluid and wavy mini-channel can boost the heat sink's hydrothermal efficiency and Ag- water nano fluid in term of heat transfer, it outperforms other nanofluids an enhancement in the Nusselt number reached to 54% at concentration volume 0.075.},
}

@article {pmid35620608,
year = {2022},
author = {Montalvo, S and Gomez, M and Lozano, A and Arias, S and Rodriguez, L and Morales-Acuna, F and Gurovich, AN},
title = {Differences in Blood Flow Patterns and Endothelial Shear Stress at the Carotid Artery Using Different Exercise Modalities and Intensities.},
journal = {Frontiers in physiology},
volume = {13},
number = {},
pages = {857816},
pmid = {35620608},
issn = {1664-042X},
support = {SC2 GM140952/GM/NIGMS NIH HHS/United States ; },
abstract = {Endothelial dysfunction is the first pathophysiological step of atherosclerosis, which is responsible for 90% of strokes. Exercise programs aim to reduce the risk of developing stroke; however, the majority of the beneficial factors of exercise are still unknown. Endothelial shear stress (ESS) is associated with endothelial homeostasis. Unfortunately, ESS has not been characterized during different exercise modalities and intensities in the carotid artery. Therefore, the purpose of this study was to determine exercise-induced blood flow patterns in the carotid artery. Fourteen apparently healthy young adults (males = 7, females = 7) were recruited for this repeated measures study design. Participants completed maximal oxygen consumption (VO2max) tests on a Treadmill, Cycle-ergometer, and Arm-ergometer, and 1-repetition maximum (1RM) tests of the Squat, Bench Press (Bench), and Biceps Curl (Biceps) on separate days. Thereafter, participants performed each exercise at 3 different exercise intensities (low, moderate, high) while a real-time ultrasound image and blood flow of the carotid artery was obtained. Blood flow patterns were assessed by estimating ESS via Womersley's estimation and turbulence via Reynold's number (Re). Data were analyzed using a linear mixed-effects model. Pairwise comparisons with Holm-Bonferroni correction were conducted with Hedge's g effect size to determine the magnitude of the difference. There was a main effect of intensity, exercise modality, and intensity * exercise modality interaction on both ESS (p < 0.001). Treadmill at a high intensity yielded the greatest ESS when compared to the other exercise modalities and intensities, while Bench Press and Biceps curls yielded the least ESS. All exercise intensities across all modalities resulted in turbulent blood flow. Clinicians must take into consideration how different exercise modalities and intensities affect ESS and Re of the carotid artery.},
}

@article {pmid35343677,
year = {2022},
author = {Chen, H and Li, Y and Wang, Y and Ning, P and Shen, Y and Wei, X and Feng, Q and Liu, Y and Li, Z and Xu, C and Huang, S and Deng, C and Wang, P and Cheng, Y},
title = {An Engineered Bacteria-Hybrid Microrobot with the Magnetothermal Bioswitch for Remotely Collective Perception and Imaging-Guided Cancer Treatment.},
journal = {ACS nano},
volume = {16},
number = {4},
pages = {6118-6133},
doi = {10.1021/acsnano.1c11601},
pmid = {35343677},
issn = {1936-086X},
mesh = {Humans ; Bacteria ; Hypoxia ; *Neoplasms/diagnostic imaging/drug therapy ; Perception ; },
abstract = {Microrobots driven by multiple propelling forces hold great potential for noninvasively targeted delivery in the physiologic environment. However, the remotely collective perception and precise propelling in a low Reynold's number bioenvironment remain the major challenges of microrobots to achieve desired therapeutic effects in vivo. Here, we reported a biohybrid microrobot that integrated with magnetic, thermal, and hypoxia sensitivities and an internal fluorescent protein as the dual reporter of thermal and positioning signals for targeted cancer treatment. There were three key elements in the microrobotic system, including the magnetic nanoparticle (MNP)-loaded probiotic Escherichia coli Nissle1917 (EcN@MNP) for spatially magnetic and hypoxia perception, a thermal-logic circuit engineered into the bacteria to control the biosynthesis of mCherry as the temperature and positioning reporter, and NDH-2 enzyme encoded in the EcN for enhanced anticancer therapy. According to the fluorescent-protein-based imaging feedback, the microrobot showed good thermal sensitivity and active targeting ability to the tumor area in a collective manner under the magnetic field. The cancer cell apoptosis was efficiently triggered in vitro and in vivo by the hybrid microrobot coupled with the effects of magnetothermal ablation and NDH-2-induced reactive oxygen species (ROS) damage. Our study demonstrates that the biohybrid EcN microrobot is an ideal platform to integrate the physical, biological, and chemical properties for collective perception and propelling in targeted cancer treatment.},
}

Humans
Bacteria
Hypoxia
*Neoplasms/diagnostic imaging/drug therapy
Perception

@article {pmid37101581,
year = {2022},
author = {Sun, R and Yu, P and Zuo, P and Alvarez, PJJ},
title = {Bacterial Concentrations and Water Turbulence Influence the Importance of Conjugation Versus Phage-Mediated Antibiotic Resistance Gene Transfer in Suspended Growth Systems.},
journal = {ACS environmental Au},
volume = {2},
number = {2},
pages = {156-165},
pmid = {37101581},
issn = {2694-2518},
abstract = {Despite the abundance of phage-borne antibiotic resistance genes (ARGs) in the environment, the frequency of ARG propagation via phage-mediated transduction (relative to via conjugation) is poorly understood. We investigated the influence of bacterial concentration and water turbulence level [quantified as Reynold's number (Re)] in suspended growth systems on the frequency of ARG transfer by two mechanisms: delivery by a lysogenic phage (phage λ carrying gentamycin-resistance gene, genR) and conjugation mediated by the self-transmissible plasmid RP4. Using Escherichia coli (E. coli) as the recipient, phage delivery had a comparable frequency (1.2 ± 0.9 × 10[-6]) to that of conjugation (1.1 ± 0.9 × 10[-6]) in suspensions with low cell concentration (10[4] CFU/mL) and moderate turbulence (Re = 5 × 10[4]). Turbulence affected cell (or phage)-to-cell contact rates and detachment (due to shear force), and thus, it affected the relative importance of conjugation versus phage delivery. At 10[7] CFU/mL, no significant difference was observed between the frequencies of ARG transfer by the two mechanisms under quiescent water conditions (2.8 ± 0.3 × 10[-5] for conjugation vs 2.2 ± 0.5 × 10[-5] for phage delivery, p = 0.19) or when Re reached 5 × 10[5] (3.4 ± 1.5 × 10[-5] for conjugation vs 2.9 ± 1.0 × 10[-5] for phage delivery, p = 0.52). Transcriptomic analysis of genes related to conjugation and phage delivery and simulation of cell (or phage)-to-cell collisions at different Re values corroborate that the importance of phage delivery relative to conjugation increases under either quiescent or turbulent conditions. This finding challenges the prevailing view that conjugation is the dominant ARG transfer mechanism and underscores the need to consider and mitigate potential ARG dissemination via transduction.},
}

@article {pmid33907644,
year = {2021},
author = {Kesserwani, H},
title = {Space Flight-Associated Neuroocular Syndrome, Idiopathic Intracranial Hypertension, and Pseudotumor Cerebri: Phenotypic Descriptions, Pathogenesis, and Hydrodynamics.},
journal = {Cureus},
volume = {13},
number = {3},
pages = {e14103},
pmid = {33907644},
issn = {2168-8184},
abstract = {Recent data from astronauts who have returned to Earth from a long-duration space flight have unequivocally distinguished spaceflight-associated neuro-ocular syndrome (SANS) from idiopathic intracranial hypertension (IIH) and pseudotumor cerebri (PTC). We review the semiology and pathogenesis of these three entities, noting that optic disc edema is what unites them, and this where the similarities between SANS and IIH/PTC end. We distinguish between PTC and IIH and between SANS and IIH/PTC and review the medical and surgical therapy of IIH/PTC. The key to understanding the phenomenon of optic disc edema is the geometry of the optic nerve sheath, which is a simulacrum of an inverted Venturi tube. This allows us to theoretically study the hydrodynamics of the optic nerve sheath by applying simple physical laws, including the Venturi effect, Poiseuille's law, and Reynold's number, and we speculate on nature's design and the correlation of form and function in understanding how cerebrospinal fluid (CSF) circulates in the optic nerve sheath as it approaches the optic nerve head. Recent spectacular data on the histology of the blood nerve-barrier of the optic nerve disc and the glymphatic system of the optic nerve sheath will also help us understand the development of optic disc edema due to the microgravity-induced cephalad shift of CSF in SANS. We will explore the role of the sodium/potassium adenosine triphosphatase (ATPase) pump on choroid plexus epithelial cells and the aquaporin-4 water receptors located on astrocyte end-feet and their complex interactions with the tetracyclines, mineralocorticoids, and therapeutic agents with carbonic anhydrase activity. We also adumbrate the complex interactions between obesity, vitamin A, and 11-beta-hydroxysteroid dehydrogenase and how the aquaporin-4 receptor relates to these interactions.},
}

@article {pmid30985778,
year = {2019},
author = {Occhicone, A and Sinibaldi, A and Sonntag, F and Munzert, P and Danz, N and Michelotti, F},
title = {Study of fluid dynamics at the boundary wall of a microchannel by Bloch surface waves.},
journal = {Optics letters},
volume = {44},
number = {8},
pages = {1932-1935},
doi = {10.1364/OL.44.001932},
pmid = {30985778},
issn = {1539-4794},
abstract = {Understanding how a fluid flows at the boundaries when it is confined at the microscale/nanoscale is crucial for a broad range of engineering and biology applications. We propose an experimental technique based on Bloch surface waves sustained by a one-dimensional photonic crystal to evaluate the speed of the contact line, i.e., the triple junction separating three phases, in the low Reynold's number regime, and with a nanometric resolution. Here, we report on the experimental characterization of the translatory motion of the contact line that separates two water solutions with a relatively high refractive index mismatch (7.35×10[-3]) and its slipping over a solid surface. The advantages are the relative simplicity and economy of the experimental configuration.},
}

@article {pmid30761361,
year = {2018},
author = {Shah, RA and Khan, A and Shuaib, M},
title = {On the study of flow between unsteady squeezing rotating discs with cross diffusion effects under the influence of variable magnetic field.},
journal = {Heliyon},
volume = {4},
number = {11},
pages = {e00925},
pmid = {30761361},
issn = {2405-8440},
abstract = {The aim of this article is to provide an analytical and numerical investigation to the viscous fluid flow, heat and mass transfer under the influence of a variable magnetic field. The governing system of partial differential equations are transformed by means of similarity transformations to a system of ordinary differential equations which are solved by Homotopy Analysis Method (HAM) and BVP4c. The effects of involved physical parameters are illustrated for the velocity components, magnetic field components, heat and mass transfers. Authentification of HAM results for various involved physical parameters are supported by comparison with numerical results obtained by BVP4c. It is observed that increasing distance between discs increase pressure on lower disc and torque on upper disc. It is also observed that increase in axial component of magnetic field increase fluid's axial velocity and increase in magnetic Reynold's number decrease magnetic flux it lower disc. Heat flux from lower to upper disc is increased by increase in Dufour number.},
}

@article {pmid30009583,
year = {2017},
author = {Malviya, R and Sharma, P and Dubey, S},
title = {Kheri (Acacia chundra, family: Mimosaceae) gum: Characterization using analytical, mathematical and pharmaceutical approaches.},
journal = {Polimery w medycynie},
volume = {47},
number = {2},
pages = {65-76},
doi = {10.17219/pim/76515},
pmid = {30009583},
issn = {0370-0747},
mesh = {Acacia/*chemistry ; Excipients ; Particle Size ; Plant Gums/*chemistry/isolation & purification ; Polysaccharides/chemistry ; Rheology ; Spectroscopy, Fourier Transform Infrared ; Viscosity ; },
abstract = {BACKGROUND: Natural polymers have been used in medical, pharmaceutical, cosmetic and food industry. They should be characterized before their possible applications in different industries.

OBJECTIVES: The objective of this study was to characterize Kheri (Acacia chundra, family: Mimosaceae) gum using analytical, mathematical and pharmaceutical approaches.

MATERIAL AND METHODS: Crude Kheri gum (KG) was purified using distilled water as a solvent and ethanol as a precipitating agent. KG was characterized in terms of phytochemical screening, micromeritic properties, microbial load, ash value, rheological behavior, solid state 1H nuclear magnetic resonance (NMR), mass spectra and Fourier-transform infrared spectroscopy (FTIR) studies for their possible applications in food, cosmetics and pharmaceutical industry.

RESULTS: Studies show that KG contains carbohydrates, while protein, fat, volatile oils, alkaloids and glycosides are absent. 1% aqueous solution of polysaccharide showed 25.58 × 103 kJ/kg activation energy and 1.39 Reynold's number. Viscosity average molecular weight of purified gum was found 1.73 × 105 D. Thermodynamic parameters, i.e., change in enthalpy ΔHv and change in enthalpy ΔHv, were found to be 12.26 × 103 kJ/mol and 24.47 kJ/mol, respectively. Mathematical approach also determined the rod shaped conformation of KG in aqueous solution. IR spectroscopic study shows the presence of free (COO-) and esterified (COO-R) carboxylic acid, ether (C-O stretching), galacturonic acid and mannose in polysaccharide 1H NMR study predicts presence of tetrahydropyran hydrogen in molecule. Furthermore, KG was also characterized as a suspending agent using paracetamol as a model drug. Flow rate, pH, particle size and settling behavior of suspensions were evaluated. Initial particle size of dispersed phase particles does not change significantly after 45 days.

CONCLUSIONS: From the findings of the research it can be concluded that KG can be used as an excipient in cosmaceuticals and pharmaceuticals and its characteristic rheological behavior may attract rheologists.},
}

Acacia/*chemistry
Excipients
Particle Size
Plant Gums/*chemistry/isolation & purification
Polysaccharides/chemistry
Rheology
Spectroscopy, Fourier Transform Infrared
Viscosity

@article {pmid28505761,
year = {2017},
author = {Pride, SR and Vasco, DW and Flekkoy, EG and Holtzman, R},
title = {Dispersive transport and symmetry of the dispersion tensor in porous media.},
journal = {Physical review. E},
volume = {95},
number = {4-1},
pages = {043103},
doi = {10.1103/PhysRevE.95.043103},
pmid = {28505761},
issn = {2470-0053},
abstract = {The macroscopic laws controlling the advection and diffusion of solute at the scale of the porous continuum are derived in a general manner that does not place limitations on the geometry and time evolution of the pore space. Special focus is given to the definition and symmetry of the dispersion tensor that is controlling how a solute plume spreads out. We show that the dispersion tensor is not symmetric and that the asymmetry derives from the advective derivative in the pore-scale advection-diffusion equation. When flow is spatially variable across a voxel, such as in the presence of a permeability gradient, the amount of asymmetry can be large. As first shown by Auriault [J.-L. Auriault et al. Transp. Porous Med. 85, 771 (2010)TPMEEI0169-391310.1007/s11242-010-9591-y] in the limit of low Péclet number, we show that at any Péclet number, the dispersion tensor D_{ij}
satisfies the flow-reversal symmetry D_{ij}(
+q)=D_{ji}(
-q) where q is the mean flow in the voxel under analysis; however, Reynold's number must be sufficiently small that the flow is reversible when the force driving the flow changes sign. We also demonstrate these symmetries using lattice-Boltzmann simulations and discuss some subtle aspects of how to measure the dispersion tensor numerically. In particular, the numerical experiments demonstrate that the off-diagonal components of the dispersion tensor are antisymmetric which is consistent with the analytical dependence on the average flow gradients that we propose for these off-diagonal components.},
}

@article {pmid27480731,
year = {2016},
author = {Akbar, NS and Butt, AW},
title = {Bio mathematical venture for the metallic nanoparticles due to ciliary motion.},
journal = {Computer methods and programs in biomedicine},
volume = {134},
number = {},
pages = {43-51},
doi = {10.1016/j.cmpb.2016.06.002},
pmid = {27480731},
issn = {1872-7565},
mesh = {Cilia/*physiology ; Computer Graphics ; Metal Nanoparticles/*chemistry ; *Models, Theoretical ; },
abstract = {BACKGROUND AND OBJECTIVES: The present investigation is associated with the contemporary study of viscous flow in a vertical tube with ciliary motion.

METHODS/RESULTS/CONCLUSIONS: The main flow problem has been modeled using cylindrical coordinates; flow equations are simplified to ordinary differential equations using longwave length and low Reynold's number approximation; and exact solutions have been obtained for velocity, pressure gradient and temperature. Results acquired are discussed graphically for better understanding. Streamlines for the velocity profile are plotted to discuss the trapping phenomenon. It is seen that with an increment in the Grashof number, the velocity of the governing fluids starts to decrease significantly.},
}

Cilia/*physiology
Computer Graphics
Metal Nanoparticles/*chemistry
*Models, Theoretical

@article {pmid25533171,
year = {2014},
author = {Astumian, RD},
title = {Enhanced diffusion, chemotaxis, and pumping by active enzymes: progress toward an organizing principle of molecular machines.},
journal = {ACS nano},
volume = {8},
number = {12},
pages = {11917-11924},
doi = {10.1021/nn507039b},
pmid = {25533171},
issn = {1936-086X},
mesh = {*Chemotaxis ; Enzymes/*isolation & purification ; *Microfluidic Analytical Techniques ; },
abstract = {Active enzymes diffuse more rapidly than inactive enzymes. This phenomenon may be due to catalysis-driven conformational changes that result in "swimming" through the aqueous solution. Recent additional work has demonstrated that active enzymes can undergo chemotaxis toward regions of high substrate concentration, whereas inactive enzymes do not, and, further, that active enzymes immobilized at surfaces can directionally pump liquids. In this Perspective, I will discuss these phenomena in light of Purcell's work on directed motion at low Reynold's number and in the context of microscopic reversibility. The conclusions suggest that a deep understanding of catalytically driven enhanced diffusion of enzymes and related phenomena can lead toward a general organizing principle for the design, characterization, and operation of molecular machines.},
}

*Chemotaxis
Enzymes/*isolation & purification
*Microfluidic Analytical Techniques

@article {pmid24973405,
year = {2014},
author = {Rembold, CM and Suratt, PM},
title = {Airway turbulence and changes in upper airway hydraulic diameter can be estimated from the intensity of high frequency inspiratory sounds in sleeping adults.},
journal = {The Journal of physiology},
volume = {592},
number = {17},
pages = {3831-3839},
pmid = {24973405},
issn = {1469-7793},
support = {M01 RR00847/RR/NCRR NIH HHS/United States ; },
mesh = {Adult ; Humans ; *Inhalation ; Larynx/pathology/*physiopathology ; Models, Biological ; Nose/pathology/*physiopathology ; Sleep Apnea, Obstructive/pathology/*physiopathology ; *Snoring ; },
abstract = {Obstructive sleep disordered breathing can cause death and significant morbidity in adults and children. We previously found that children with smaller upper airways (measured by magnetic resonance imaging while awake) generated loud high frequency inspiratory sounds (HFIS, defined as inspiratory sounds > 2 kHz) while they slept. The purpose of this study was (1) to determine what characteristics of airflow predicted HFIS intensity, and (b) to determine if we could calculate changes in hydraulic diameter (D) in both an in vitro model and in the upper airways of sleeping humans. In an in vitro model, high frequency sound intensity was an estimate of airflow turbulence as reflected by the Reynold's number (Re). D of the in vitro model was calculated using Re, the pressure gradient, Swamee-Jain formula and Darcy formula. D was proportional to but smaller than the actual diameters (r(2) = 0.94). In humans, we measured HFIS intensity and the pressure gradient across the upper airway (estimated with oesophageal pressure, Pes) during polysomnography in four adult volunteers and applied the same formulae to calculate D. At apnoea termination when the airway opens, we observed (1) an increase in HFIS intensity suggesting an increase in turbulence (higher Re), and (2) a larger calculated D. This method allows dynamic estimation of changes in relative upper airway hydraulic diameter (D) in sleeping humans with narrowed upper airways.},
}

Adult
Humans
*Inhalation
Larynx/pathology/*physiopathology
Models, Biological
Nose/pathology/*physiopathology
Sleep Apnea, Obstructive/pathology/*physiopathology
*Snoring

@article {pmid23325520,
year = {2014},
author = {Nocke, H and Meyer, F and Lessmann, V},
title = {[Aspects of vascular physiology in clinical and vascular surgical practice: basic principles of vascular mechanics].},
journal = {Zentralblatt fur Chirurgie},
volume = {139},
number = {5},
pages = {499-507},
doi = {10.1055/s-0032-1327967},
pmid = {23325520},
issn = {1438-9592},
mesh = {Blood Pressure/*physiology ; Cardiovascular Diseases/*physiopathology/*surgery ; *Cardiovascular Physiological Phenomena ; Hemodynamics/*physiology ; Humans ; Models, Cardiovascular ; Muscle, Smooth, Vascular/*physiopathology ; Pulsatile Flow/*physiology ; Reference Values ; Vascular Stiffness/*physiology ; },
abstract = {To be able to evaluate properly a vascular problem, basic concepts of vascular physiology need to be considered, as they have been taught in physiology for a long time. This article deals with selected definitions and laws of passive vascular mechanics, subdivided into parameters of vascular filling and parameters of vascular flow. PARAMETERS OF VASCULAR FILLING: During vascular filling the transmural pressure distends the vascular wall until it is balanced by the wall tension. The extent of this distension up to the point of balance depends on the elasticity of the wall. Transmural pressure, wall tension and elasticity are defined, and their respective importance is described by clinical examples, e.g. aneurysm and varix. PARAMETERS OF VASCULAR FLOW: The vascular flow can be divided into stationary and pulsating components. Both components are relevant for the bloodstream. Since the blood flow is directed in the circuit, it can be understood in first approximation as stationary ("direct current").The direct current model uses only the average values of the pulsating variables. The great advantage of the direct current model is that it can be described with simple laws, which are not valid without reservation, but often allow a first theoretical approach to a vascular problem: Ohm's law, driving pressure, flow resistance, Hagen-Poiseuille law, wall shear stress, law of continuity, Bernoulli's equation and Reynold's number are described and associated with clinical examples.The heart is a pressure-suction pump and produces a pulsating flow, the pulse. The pulse runs with pulse wave velocity, which is much larger than the blood flow velocity, through the arterial vascular system. During propagation, the pulse has to overcome the wave resistance (impedance). Wherever the wave resistance changes, e.g., at vascular bifurcations and in the periphery, it comes to reflections. The incident (forward) and reflected (backward) waves are superimposed to yield the resulting pulse wave. This pulse wave allows one to distinguish pressure and flow pulse by measurement. Both are described separately, and their respective clinical meaning is illustrated by appropriate examples, e.g., arterial stiffness and pre-/postocclusive high/low resistance flow, respectively.},
}

Blood Pressure/*physiology
Cardiovascular Diseases/*physiopathology/*surgery
*Cardiovascular Physiological Phenomena
Hemodynamics/*physiology
Humans
Models, Cardiovascular
Muscle, Smooth, Vascular/*physiopathology
Pulsatile Flow/*physiology
Reference Values
Vascular Stiffness/*physiology

@article {pmid22852428,
year = {2012},
author = {Karadagli, F and Rittmann, BE and McAvoy, DC and Richardson, JE},
title = {Effect of turbulence on the disintegration rate of flushable consumer products.},
journal = {Water environment research : a research publication of the Water Environment Federation},
volume = {84},
number = {5},
pages = {424-433},
doi = {10.2175/106143012x13354606450960},
pmid = {22852428},
issn = {1061-4303},
mesh = {*Environmental Restoration and Remediation ; *Household Products ; Hydrodynamics ; *Waste Disposal, Fluid ; },
abstract = {A previously developed model for the physical disintegration of flushable consumer products is expanded by investigating the effects of turbulence on the rate of physical disintegration. Disintegration experiments were conducted with cardboard tampon applicators at 100, 150, and 200 rotations per minute, corresponding to Reynold's numbers of 25,900, 39,400, and 52,900, respectively, which were estimated by using computational fluid dynamics modeling. The experiments were simulated with the disintegration model to obtain best-fit values of the kinetic and distribution parameters. Computed rate coefficients (ki) for all solid sizes (i.e., greater than 8, 4 to 8, 2 to 4, and 1 to 2 mm) increased strongly with Reynold's number or rotational speed. Thus, turbulence strongly affected the disintegration rate of flushable products, and the relationship of the ki values to Reynold's number can be included in mathematical representations of physical disintegration.},
}

*Environmental Restoration and Remediation
*Household Products
Hydrodynamics
*Waste Disposal, Fluid

@article {pmid22779677,
year = {2012},
author = {Raghu, RC and Schofield, J},
title = {Simulation of tethered oligomers in nanochannels using multi-particle collision dynamics.},
journal = {The Journal of chemical physics},
volume = {137},
number = {1},
pages = {014901},
doi = {10.1063/1.4731662},
pmid = {22779677},
issn = {1089-7690},
abstract = {The effect of a high Reynold's number, pressure-driven flow of a compressible gas on the conformation of an oligomer tethered to the wall of a square channel is studied under both ideal solvent and poor solvent conditions using a hybrid multiparticle collision dynamics and molecular dynamics algorithm. Unlike previous studies, the flow field contains an elongational component in addition to a shear component as well as fluid slip near the walls and results in a Schmidt number for the polymer beads that is less than unity. In both solvent regimes the oligomer is found to extend in the direction of flow. Under the ideal solvent conditions, torsional twisting of the chain and aperiodic cyclical dynamics are observed for the end of the oligomer. Under poor solvent conditions, a metastable helix forms in the end of the chain despite the lack of any attractive potential between beads in the oligomeric chain. The formation of the helix is postulated to be the result of a solvent induced chain collapse that has been confined to a single dimension by a strong flow field.},
}

@article {pmid22538166,
year = {2012},
author = {Banerjee, S and Sutanto, S and Kleijn, JM and van Roosmalen, MJ and Witkamp, GJ and Stuart, MA},
title = {Colloidal interactions in liquid CO2--a dry-cleaning perspective.},
journal = {Advances in colloid and interface science},
volume = {175},
number = {},
pages = {11-24},
doi = {10.1016/j.cis.2012.03.005},
pmid = {22538166},
issn = {1873-3727},
mesh = {Carbon Dioxide/*chemistry ; *Clothing ; Colloids/chemistry ; Detergents/*chemistry ; Soil/analysis/chemistry ; Solvents/chemistry ; Surface-Active Agents/chemistry ; Tetrachloroethylene/*chemistry ; Water/chemistry ; },
abstract = {Liquid CO(2) is a viable alternative for the toxic and environmentally harmful solvents traditionally used in dry-cleaning industry. Although liquid CO(2) dry-cleaning is being applied already at a commercial scale, it is still a relatively young technique which poses many challenges. The focus of this review is on the causes of the existing problems and directions to solve them. After presenting an overview of the state-of-the-art, we analyze the detergency challenges from the fundamentals of colloid and interface science. The properties of liquid CO(2) such as dielectric constant, density, Hamaker constant, refractive index, viscosity and surface tension are presented and in the subsequent chapters their effects on CO(2) dry-cleaning operation are delineated. We show, based on theory, that the van der Waals forces between a model soil (silica) and model fabric (cellulose) through liquid CO(2) are much stronger compared to those across water or the traditional dry-cleaning solvent PERC (perchloroethylene). Prevention of soil particle redeposition in liquid CO(2) by electrostatic stabilization is challenging and the possibility of using electrolytes having large anionic parts is discussed. Furthermore, the role of different additives used in dry-cleaning, such as water, alcohol and surfactants, is reviewed. Water is not only used as an aid to remove polar soils, but also enhances adhesion between fabric and soil by forming capillary bridges. Its role as a minor component in liquid CO(2) is complex as it depends on many factors, such as the chemical nature of fabrics and soil, and also on the state of water itself, whether present as molecular solution in liquid CO(2) or phase separated droplets. The phenomena of wicking and wetting in liquid CO(2) systems are predicted from the Washburn-Lucas equation for fabrics of various surface energies and pore sizes. It is shown that nearly complete wetting is desirable for good detergency. The effect of mechanical action and fluid dynamic conditions on dry-cleaning is analyzed theoretically. From this it follows that in liquid CO(2) an order of magnitude higher Reynold's number is required to exceed the binding forces between fabric and soil as opposed to PERC or water, mainly due to the strong van der Waals forces and the low viscosity of CO(2) at dry-cleaning operational conditions.},
}

Carbon Dioxide/*chemistry
*Clothing
Colloids/chemistry
Detergents/*chemistry
Soil/analysis/chemistry
Solvents/chemistry
Surface-Active Agents/chemistry
Tetrachloroethylene/*chemistry
Water/chemistry

@article {pmid21491262,
year = {2011},
author = {Nadeem, S and Akbar, NS and Hayat, T and Hendi, AA},
title = {Numerical and series solutions of the peristaltic motion of an Oldroyd 8-constant fluid in an endoscope.},
journal = {Computer methods in biomechanics and biomedical engineering},
volume = {14},
number = {11},
pages = {987-993},
doi = {10.1080/10255842.2010.503960},
pmid = {21491262},
issn = {1476-8259},
mesh = {*Endoscopes ; *Models, Theoretical ; *Peristalsis ; },
abstract = {In the present article, we have presented the peristaltic flow of an Oldroyd 8-constant fluid in an endoscope. The governing equations for the flow problem are simplified using long wavelength and low Reynold's number approximations. The solutions of the simplified problem are calculated using (i) Homotopy analysis method and (ii) Shooting method. The comparison of both the solutions shows a very good agreement between the results. The graphical results for the velocity field and stresses are presented to show the physical behaviour of all the parameters appearing in the problem.},
}

*Endoscopes
*Models, Theoretical
*Peristalsis

@article {pmid18471808,
year = {2008},
author = {Jayalalitha, G and Shanthoshini Deviha, V and Uthayakumar, R},
title = {Fractal model for blood flow in cardiovascular system.},
journal = {Computers in biology and medicine},
volume = {38},
number = {6},
pages = {684-693},
doi = {10.1016/j.compbiomed.2008.03.002},
pmid = {18471808},
issn = {0010-4825},
mesh = {Algorithms ; Blood Flow Velocity/physiology ; Blood Pressure/physiology ; *Computer Simulation ; Coronary Circulation/*physiology ; Elasticity ; *Fractals ; Heart/anatomy & histology ; Humans ; Models, Anatomic ; *Models, Cardiovascular ; Vascular Resistance/physiology ; },
abstract = {Blood flow in the cardiovascular system is the central point of experimental and theoretical investigation. The objective of the study is to determine the blood flow in the cardiovascular system using Darcy's law, Reynold's number and Poiseuille's equation. A possible way of modeling of self-similar biological tree-like structure is proposed. Special attention is paid to the blood vessel system, with elaboration on a model with certain spatial arrangement of the vessels and reasonable dependence of the blood pressure on the vessels diameter such that the organism has a homogeneous oxygen supply. Flow analysis in the above systems is analyzed by invasion percolation. The blood flow in the cardiovascular system has been numerically calculated for both normal and abnormal patients. A new algorithm has been introduced to visit the blood vessels in a robust manner which avoids loops and provides us the results in a simple manner.},
}

Algorithms
Blood Flow Velocity/physiology
Blood Pressure/physiology
*Computer Simulation
Coronary Circulation/*physiology
Elasticity
*Fractals
Heart/anatomy & histology
Humans
Models, Anatomic
*Models, Cardiovascular
Vascular Resistance/physiology

@article {pmid18273548,
year = {2008},
author = {Yamaguchi, R and Ujiie, H and Haida, S and Nakazawa, N and Hori, T},
title = {Velocity profile and wall shear stress of saccular aneurysms at the anterior communicating artery.},
journal = {Heart and vessels},
volume = {23},
number = {1},
pages = {60-66},
pmid = {18273548},
issn = {0910-8327},
mesh = {Blood Flow Velocity/*physiology ; Cerebrovascular Circulation/*physiology ; Humans ; Intracranial Aneurysm/*physiopathology ; Laser-Doppler Flowmetry ; Models, Theoretical ; Severity of Illness Index ; Shear Strength ; Stress, Mechanical ; },
abstract = {It has recently been shown that the aspect ratio (dome/neck) of an aneurysm correlates well with intraaneurysmal blood flow. Aneurysms with an aspect ratio larger than 1.6 carry a higher risk of rupture. We examined the effect of aspect ratio (AR) on intra-aneurysmal flow using experimental models. Flow visualization with particle imaging velocimetry and measurement of wall shear stress using laser Doppler anemometry were performed on three different aneurysm models: AR 0.5, 1.0, and 2.0. Intraaneurysmal flow consists of inflow, circulation, and outflow. Rapid inflow impinged on the distal neck creating a stagnant point. Rapid flow and maximum wall shear stress were observed in the vicinity of the stagnant point. By changing the Reynold's number, the stagnant point moved. By increasing the AR of the aneurysm, vortices inside the aneurysm sac closed and very slow flow was observed, resulting in very low shear stress markedly at a Reynold's number of 250, compatible with the diastolic phase. In the aneurysm model AR 2.0, both rapid flow at the neck and vortices inside the aneurysm are sufficient to activate platelets, making a thrombus that may anchor on the dome where very slow flow takes place. Hemodynamics in aneurysms larger than AR 2.0 definitely contribute to thrombus formation.},
}

Blood Flow Velocity/*physiology
Cerebrovascular Circulation/*physiology
Humans
Intracranial Aneurysm/*physiopathology
Laser-Doppler Flowmetry
Models, Theoretical
Severity of Illness Index
Shear Strength
Stress, Mechanical

@article {pmid16883682,
year = {2006},
author = {Wu, Y and Ghaly, ES},
title = {Effect of hydrodynamic environment on tablet dissolution using flow-through dissolution apparatus.},
journal = {Puerto Rico health sciences journal},
volume = {25},
number = {1},
pages = {75-83},
pmid = {16883682},
issn = {0738-0658},
mesh = {Solubility ; *Tablets ; Water ; },
abstract = {The main objective of this research is to investigate the principles underlying the dissolution process, study the phenomena of drug release in laminar flow, and better understand the effect of hydrodynamic condition on drug dissolution, in order to predict drug dissolution from a solid dosage form. Two drug models were selected, theophylline (Class I) and naproxen (Class II), and were formulated into conventional tablets containing 105 mg theophylline or 300 mg naproxen using wet granulation method. Additionally theophylline (105 mg) and naproxen (300 mg) matrices containing 30% hydroxypropylmethylcellulose (HPMC) polymer were prepared by direct compression and tested for dissolution using both USP II and IV dissolution apparatus. Tablets were tested for dissolution (USP IV) using different cell diameter, flow rate, and different position of the tablet inside the cell. In general, the drug dissolution at a given time is a direct function of the flow rate, increasing the flow rate increases drug release. The use of a small cell resulted in faster drug dissolution and higher Reynold's Number than using a large cell. Tablet position in the cell, also has an effect on drug dissolution, inserting the tablet in a horizontal position inside the cell gave faster dissolution than a vertical position. The hydrodynamic conditions did not affect the drug dissolution from HPMC controlled release tablets indicating that the drug dissolution is controlled by the matrix. An equation to predict drug dissolution from conventional tablets was established: Sh=-21.36+10.58Re(1/2) where R2=0.98. This study demonstrated that hydrodynamic conditions, and type of dissolution testing apparatus used have an effect on dissolution rate, mass transfer rate, and film thickness underlying dissolution process.},
}

Solubility
*Tablets
Water

@article {pmid11522303,
year = {2001},
author = {Long, Q and Xu, XY and Ramnarine, KV and Hoskins, P},
title = {Numerical investigation of physiologically realistic pulsatile flow through arterial stenosis.},
journal = {Journal of biomechanics},
volume = {34},
number = {10},
pages = {1229-1242},
doi = {10.1016/s0021-9290(01)00100-2},
pmid = {11522303},
issn = {0021-9290},
mesh = {Arterial Occlusive Diseases/*physiopathology ; Blood Flow Velocity ; *Computer Simulation ; Humans ; *Models, Cardiovascular ; Pulsatile Flow/*physiology ; Stress, Mechanical ; },
abstract = {Numerical simulations of pulsatile blood flow in straight tube stenosis models were performed to investigate the poststenotic flow phenomena. In this study, three axisymmetrical and three asymmetrical stenosis models with area reduction of 25%, 50% and 75% were constructed. A measured human common carotid artery blood flow waveform was used as the upstream flow condition which has a mean Reynold's number of 300. All calculations were performed with high spatial and temporal resolutions. Flow features such as velocity profiles, flow separation zone (FSZ), and wall shear stress (WSS) distributions in the poststenotic region for all models are presented. The results have demonstrated that the formation and development of FSZs in the poststenotic region are very complex, especially in the flow deceleration phase. In axisymmetric stenoses the poststenotic flow is more sensitive to changes in the degree of stenosis than in asymmetric models. For severe stenoses, the stenosis influence length is shorter in asymmetrical models than in axisymmetrical cases. WSS oscillations (between positive and negative values) have been observed at various downstream locations in some models. The amplitude of the oscillation depends strongly on the axial location and the degree of stenosis.},
}

Arterial Occlusive Diseases/*physiopathology
Blood Flow Velocity
*Computer Simulation
Humans
*Models, Cardiovascular
Pulsatile Flow/*physiology
Stress, Mechanical

@article {pmid10878326,
year = {2000},
author = {Cammarn, SR and Sakr, A},
title = {Predicting dissolution via hydrodynamics: salicylic acid tablets in flow through cell dissolution.},
journal = {International journal of pharmaceutics},
volume = {201},
number = {2},
pages = {199-209},
doi = {10.1016/s0378-5173(00)00415-4},
pmid = {10878326},
issn = {0378-5173},
mesh = {Models, Theoretical ; Pharmacopoeias as Topic ; Salicylic Acid/administration & dosage/*chemistry ; Solubility ; Solvents ; Spectrophotometry, Ultraviolet ; Tablets ; United States ; },
abstract = {A model was established for the dissolution of non-disintegrating salicylic acid tablets as a function of hydrodynamic conditions in the Flow Through Cell system (USP Apparatus 4). The approach was to model the dissolution rate of the material as a function of the Reynold's number, the dimensionless engineering term that describes the degree of turbulence. The dissolution rate of USP calibrator salicylic acid tablets was measured as a function of tablet size, orientation within the cell, dissolution media flow rate, and cell size. All of these variables were found to have an effect on dissolution rate, consistent with theory. An equation to predict this dissolution was established as: N(SH)=-21.1+12.6xN(RE)(0.5), R(2)=0.99; 10 }

Models, Theoretical
Pharmacopoeias as Topic
Salicylic Acid/administration & dosage/*chemistry
Solubility
Solvents
Spectrophotometry, Ultraviolet
Tablets
United States

@article {pmid9496765,
year = {1996},
author = {Hrncír, E},
title = {Flow resistance of airways under hyperbaric conditions.},
journal = {Physiological research},
volume = {45},
number = {2},
pages = {153-158},
pmid = {9496765},
issn = {0862-8408},
mesh = {*Air Pressure ; Airway Resistance/*physiology ; Gases ; Humans ; Models, Biological ; Trachea/anatomy & histology/physiology ; Viscosity ; },
abstract = {Based on the known relations governing flow resistance of a tube during laminar and turbulent flow and the value of the so-called Reynold's number the following conclusions were derived: 1. The flow resistance of airways increases under hyperbaric conditions because a) the turbulent flow participates in the airways to a greater extent due to its gradual extension to minor airways, and b) during turbulent flow the flow resistance is directly proportional to the pressure of the inhaled gas. 2. If the pressure in the surrounding environment increases n-times, this has an impact on the distribution of laminar and turbulent flow in the airways and their flow resistance, similarly as if the flow rates would increase n-times under normobaric conditions. 3. Dynamic indicators of lung ventilation corresponding to higher flow rates (e.g. PEF - peak expiratory flow) are reduced under hyperbaric conditions to a greater extent than the dynamic parameters corresponding to lower flow rates (e.g. FMEF25-75 - forced midexpiratory flow) determined usually by conditions in the minor airways, where the flow usually remains laminar or intermediate.},
}

*Air Pressure
Airway Resistance/*physiology
Gases
Humans
Models, Biological
Trachea/anatomy & histology/physiology
Viscosity

@article {pmid8746940,
year = {1995},
author = {Wellnhofer, E and Biamino, G and Sauer, HU and Trebeljahr, A and Stalke, J and Ragg, C and Oswald, H and Gotze, S and Fleck, E and Felix, R},
title = {Changes of fluid-dynamic parameters in peripheral stenoses with transcutaneous interventions.},
journal = {European heart journal},
volume = {16 Suppl J},
number = {},
pages = {60-70},
doi = {10.1093/eurheartj/16.suppl_j.60},
pmid = {8746940},
issn = {0195-668X},
mesh = {Adult ; Aged ; Aged, 80 and over ; Angiography ; *Angioplasty, Balloon, Laser-Assisted ; Blood Flow Velocity ; Blood Viscosity ; Exercise Test ; Female ; Humans ; Male ; Middle Aged ; Peripheral Vascular Diseases/diagnosis/*physiopathology/therapy ; Ultrasonography, Interventional ; },
abstract = {UNLABELLED: Peripheral vessels provide a useful in vivo haemodynamic model allowing evaluation of local intravascular fluid dynamics. Velocity measurements using a 0.018 inch Doppler-tipped angioplasty guidewire, quantitative angiography and laboratory data were gathered from 45 patients with a total of 48 percutaneous transluminal laser assisted angioplasties (PTLA) in the superficial femoral, in the iliac, in the popliteal artery and in the peroneal artery. From these data, blood flow, whole blood viscosity, Reynold's numbers, Womersley numbers and shear stress were calculated, evaluated as to their changes post PTLA and correlated with clinical improvement at early follow-up. The clinical result was quantified as categorial improvement according to the American Heart Association guidelines. The primary angiographic results of angioplasty were satisfactory in all patients. Clinically 17/45 patients showed a marked, 6/45 a moderate, 18/45 a minimal, and 4/45 no improvement. The mean values of maximal peak velocity at stenosis decreased from 235 +/- 28 cms-1 to 84 +/- 8 cms-1 after PTLA (P < 0.01). The minimal intrastenotic cross section increased from 7.7 +/- 0.9 to 21.9 +/- 1.6 mm2 (P < 0.01). Mean trans-stenotic flow increased after intervention by about 50% (P < 0.01) and improved further by 135% after administration of adenosine triphosphosphate i.a. (P < 0.01). Reynold's numbers were elevated intrastenotically (1285 +/- 198) pre-intervention as compared to values proximal (564 +/- 81) and distal (449 +/- 66) to the stenosis and were reduced significantly (P < 0.05) at stenosis by PTLA, whereas values proximally and distally increased significantly (P < 0.01) post PTLA (proximal 829 +/- 84, intra 773 +/- 107, distal 676 +/- 98). Shear stress, reflecting mechanical interaction between flow and vessel wall, was elevated at stenosis pre-intervention to 44 +/- 8.9 Pa and reduced at post-stenoric vessel sites to 2.4 +/- 0.5 Pa. PTLA caused a decrease in stenosis to 6.3 +/- 1 Pa (P < 0.01) and an increase distally to 4.6 +/- 1 Pa (P < 0.01). Whereas in single stenoses removal of the obstruction was associated with a significant (P < 0.05) increase in trans-stenotic flow and shear stress distally, there was only auenuated increase in trans-stenotic flow in multiple lesions despite an angiographically good PTLA result. Shear stress distally remained low in those patients. Velocities and Reynold's numbers were lower in these vessels even pre PTLA. Residual flow, Reynold's number and minimal cross-section pre-intervention correlated significantly with clinical outcome. Pooling cases with no or minimal, as opposed to those with marked or moderate improvement, 81% of patients were correctly classified using the Reynold's numbers pre- and post-PTLA.

CONCLUSION: Peak velocity monitoring is feasible and safe during angioplasty. Velocity provides clinically relevant physiological information in addition to angiography. Combining quantitative angiography, velocity measurements and laboratory data allow the calculation of blood flow, Reynold's numbers and shear stress, thereby providing complex fluid dynamic information. Thus the evaluation of haemo-dynamics in single and multiple obstructions before and after intervention is improved. Fluid dynamic parameters pre-and post-PTLA are significantly correlated with clinical short-term result.},
}

Adult
Aged
Aged, 80 and over
Angiography
*Angioplasty, Balloon, Laser-Assisted
Blood Flow Velocity
Blood Viscosity
Exercise Test
Female
Humans
Male
Middle Aged
Peripheral Vascular Diseases/diagnosis/*physiopathology/therapy
Ultrasonography, Interventional

@article {pmid7877228,
year = {1995},
author = {Staalsen, NH and Ulrich, M and Winther, J and Pedersen, EM and How, T and Nygaard, H},
title = {The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.},
journal = {Journal of vascular surgery},
volume = {21},
number = {3},
pages = {460-471},
doi = {10.1016/s0741-5214(95)70288-1},
pmid = {7877228},
issn = {0741-5214},
mesh = {Anastomosis, Surgical/*methods ; Animals ; Aorta/diagnostic imaging/physiology/*surgery ; *Blood Flow Velocity ; Blood Vessel Prosthesis ; Hemodynamics ; Hemorheology ; Swine ; Ultrasonography, Doppler, Color ; },
abstract = {PURPOSE: The purpose of this article was to study the influence of the anastomosis angle on the flow fields at end-to-side anastomoses in vivo.

METHODS: Polyurethane grafts of similar internal diameter to that of the abdominal aorta (8 mm) were implanted from the suprarenal to the infrarenal level in 10 pigs. Three angles of standardized distal end-to-side anastomoses (90 degrees, 45 degrees, and 15 degrees) were studied. The anatomic position of the anastomoses was constant, the proximal outflow segment was occluded, and the flow rate through the graft was controlled. Flow visualization was accomplished by a color-flow Doppler ultrasound system.

RESULTS: The angulation was reproduced within 10%. Gross hemodynamic parameters were stable, and the similarity parameters were typical for peripheral bypasses (mean Reynold's number is 424 and Womersley's parameter is 5.9). The flow fields were clearly dependent on the anastomosis angle. A zone of recirculation (approximately 5% of the flow area), extending from the toe to one diameter downstream, was found in the 45-degree and 90-degree anastomoses. No flow disturbances were detected at the toe and one diameter downstream with an anastomosis angle of 15 degrees. At the heel different recirculating flow patterns were found in the different anastomoses.

CONCLUSION: The anastomosis angle does change the flow fields at vascular end-to-side anastomoses in vivo.},
}

Anastomosis, Surgical/*methods
Animals
Aorta/diagnostic imaging/physiology/*surgery
*Blood Flow Velocity
Blood Vessel Prosthesis
Hemodynamics
Hemorheology
Swine
Ultrasonography, Doppler, Color

@article {pmid8125899,
year = {1993},
author = {Quail, AW and Cottee, DB and White, SW},
title = {Limitations of a pulsed Doppler velocimeter for blood flow measurement in small vessels.},
journal = {Journal of applied physiology (Bethesda, Md. : 1985)},
volume = {75},
number = {6},
pages = {2745-2754},
doi = {10.1152/jappl.1993.75.6.2745},
pmid = {8125899},
issn = {8750-7587},
mesh = {Animals ; Aorta, Abdominal/physiology ; Coronary Circulation/physiology ; Dogs ; Femoral Artery/physiology ; Hematocrit ; Microcirculation/*physiology ; Rabbits ; Renal Artery/physiology ; Rheology/*instrumentation ; Ultrasonics ; },
abstract = {The performance of a new and simplified flow probe construction and the Iowa 545C-4 pulsed Doppler velocimeter was evaluated for measurement of blood flow over several months in small arteries of awake animals. Calibrations were performed over a wide range of intraluminal pressures and physiological flow velocities. Pressure-dependent differences in slope of the Doppler shift-volume flow relationship were detected in some probes. Signal strength was maintained at hematocrits > 10%. Distortion of pulsed Doppler signal peaks occurred in the conscious rabbit at peak aortic velocities, at which Reynold's number for turbulence was exceeded and the Doppler shift surpassed the Nyquist limit of 31.25 kHz for the velocimeter. Although the Doppler shift-volume flow relationship is linear at < 5 kHz, in some cases at higher Doppler shifts and blood flow velocities the relationship may become nonlinear, thus causing the volume flow rate to be underestimated by up to 38%. The cause of this phenomenon may be "aliasing" and/or the consequence of the range control capability of the velocimeter selectively sampling changing velocity profiles and flow disturbances in the central stream at higher velocities.},
}

Animals
Aorta, Abdominal/physiology
Coronary Circulation/physiology
Dogs
Femoral Artery/physiology
Hematocrit
Microcirculation/*physiology
Rabbits
Renal Artery/physiology
Rheology/*instrumentation
Ultrasonics

@article {pmid8511826,
year = {1993},
author = {Bascom, PA and Cobbold, RS and Routh, HF and Johnston, KW},
title = {On the Doppler signal from a steady flow asymmetrical stenosis model: effects of turbulence.},
journal = {Ultrasound in medicine & biology},
volume = {19},
number = {3},
pages = {197-210},
doi = {10.1016/0301-5629(93)90110-a},
pmid = {8511826},
issn = {0301-5629},
mesh = {*Blood Flow Velocity ; Constriction ; Humans ; *Models, Cardiovascular ; Models, Structural ; Rheology ; *Ultrasonography ; },
abstract = {A steady flow model with a 70% (by area) asymmetrical stenosis was used to examine how changing flow regimes (laminar to turbulent) affect the Doppler signal. Human red blood cells (RBCs) (Hct = 42%) in saline were employed at a flow rate corresponding to a Reynold's number of approximately 545. A dilute suspension of 4% fixed RBCs was also used for the purpose of backscattered power comparison. Measurements of the Doppler signal enabled the backscattered power, time domain statistics, frequency spectra, frequency domain statistics, various spectral indices, autocorrelation function and decorrelation time to be calculated as a function of distance from the stenosis. It is shown that the characteristics of the Doppler signal measured at each site provide information on the nature of the insonated flow field and these correlate well with those expected. The results demonstrate that the onset of turbulence not only affects the Doppler spectrum but also has a profound effect on the signal power, the decorrelation time and the signal statistics.},
}

*Blood Flow Velocity
Constriction
Humans
*Models, Cardiovascular
Models, Structural
Rheology
*Ultrasonography

@article {pmid2252781,
year = {1990},
author = {Van Meurs, KP and Mikesell, GT and Seale, WR and Short, BL and Rivera, O},
title = {Maximum blood flow rates for arterial cannulae used in neonatal ECMO.},
journal = {ASAIO transactions},
volume = {36},
number = {3},
pages = {M679-81},
pmid = {2252781},
issn = {0889-7190},
mesh = {Blood Flow Velocity/*physiology ; *Catheters, Indwelling ; Equipment Design ; Erythrocyte Deformability/*physiology ; Extracorporeal Membrane Oxygenation/*instrumentation ; Hemolysis/*physiology ; Humans ; Infant, Newborn ; Models, Cardiovascular ; Respiratory Distress Syndrome, Newborn/*physiopathology ; Rheology ; },
abstract = {The arterial cannulae used in neonatal ECMO cause hemolysis and red blood cell damage at elevated blood flows. Hemolysis in extracorporeal circuits has been found to occur with shear stress greater than 132 dynes/cm2, turbulence as measured by Reynold's number greater than 1,000, and velocity greater than 120 to 200 cm/sec. These parameters need to be considered when sizing the proper arterial cannula for a required flow rate. In-vitro measurements of the pressure drop across six arterial cannulae at varying flow rates were performed using human blood with a hematocrit of 43%. Shear stress, Reynold's number, velocity, and pressure drop were calculated for each catheter at flow rates from 50 to 1,000 cc/min. The maximum mean flow rate to maintain the shear stress, Reynold's number, velocity, and pressure drop within the accepted range, was determined for each cannula. Recommended maximum blood flow rates for each of the six cannulae are given. Internal diameter, length, and cannula geometry appear to be the factors most affecting the flow achievable without causing red blood cell damage and hemolysis. Ten French Biomedicus, 10 French Cook, and 10 French Elecath arterial cannulae appear best suited to deliver the range of blood flow rates used in neonatal ECMO.},
}

Blood Flow Velocity/*physiology
*Catheters, Indwelling
Equipment Design
Erythrocyte Deformability/*physiology
Extracorporeal Membrane Oxygenation/*instrumentation
Hemolysis/*physiology
Humans
Infant, Newborn
Models, Cardiovascular
Respiratory Distress Syndrome, Newborn/*physiopathology
Rheology

@article {pmid2780523,
year = {1989},
author = {Vogel, J and Smith, HJ and Müller, E},
title = {[To what extent are oscillometric data of a simple resistor-volume model physically recordable?].},
journal = {Pneumologie (Stuttgart, Germany)},
volume = {43},
number = {7},
pages = {324-330},
pmid = {2780523},
issn = {0934-8387},
mesh = {*Airway Resistance ; Algorithms ; Humans ; Lung/physiopathology ; Lung Volume Measurements/*instrumentation ; *Models, Biological ; Oscillometry/*instrumentation ; Pulmonary Emphysema/physiopathology ; *Pulmonary Ventilation ; },
abstract = {To obtain data on the volume-dependence of the oscillatory parameters of the Siregnost FD 5, we investigated the course of iso-volume and iso-resistance lines in a simple mechanical resistor-volume model in the different coordinate systems, initially in the absence of additional superimposed stationary flow. While the P-psi diagram reveals no uniform course, and no preferential relationship of changes in resistance to P or Ros, or of changes in volume to psi, such a relationship develops on transformation to the Rre-phi and the Rre-X diagram. Rre proves to contain not only the purely resistor component, but also a reactance-proportional or inversely volume-proportional component, which is apparently due to internal friction resulting from volume compression. On the other hand, reactance is almost totally derivable from volume compression. With reference to the theoretical Franken model and others (1981), we discussed the influence of various physical factors on the impedance of a tube segment, and the different volume-dependence of impedance of closed- and open-ended cylindrical tubes. Further work on the theoretical consideration of the forced oscillation technique will examine the influence of additional superimposed stationary flow, which has a considerable effect on the resistor-volume model. Furthermore, the critical value of Reynold's number may be expected to be exceed in the FD 5 reference tube already at low respiratory flow.},
}

*Airway Resistance
Algorithms
Humans
Lung/physiopathology
Lung Volume Measurements/*instrumentation
*Models, Biological
Oscillometry/*instrumentation
Pulmonary Emphysema/physiopathology
*Pulmonary Ventilation

@article {pmid2949490,
year = {1986},
author = {Steiger, HJ and Reulen, HJ},
title = {Low frequency flow fluctuations in saccular aneurysms.},
journal = {Acta neurochirurgica},
volume = {83},
number = {3-4},
pages = {131-137},
pmid = {2949490},
issn = {0001-6268},
mesh = {*Cerebrovascular Circulation ; Humans ; Intracranial Aneurysm/*physiopathology ; Models, Biological ; Rheology ; Rupture, Spontaneous ; },
abstract = {Intra-operative Doppler recordings were carried out on cerebral saccular aneurysms in 12 patients. Distinct fluctuations of flow superimposed on the pulse wave were seen in 6 patients. The fluctuations appeared to be periodic with measured period lengths of 60 to 150 msec. In 3 other patients flow irregularities could be discerned acoustically but a definite periodicity could not be visualized on screen. In 3 patients flow appeared smooth during the entire pulse cycle, acoustically as well as visually. Concomitant flow observations in glass model aneurysms also revealed flow instabilities in certain aneurysm types at a Reynold's number of 300. All observed irregularities of flow were observed in zones of deceleration of flow in the models. Signs of fully developed turbulence were not found, neither in human aneurysms nor in the glass models. It appears likely that the fluctuations of flow induce vibrations of the aneurysmal wall and contribute to aneurysm progression and eventual rupture.},
}

*Cerebrovascular Circulation
Humans
Intracranial Aneurysm/*physiopathology
Models, Biological
Rheology
Rupture, Spontaneous

@article {pmid6747536,
year = {1984},
author = {Batty, RS},
title = {Development of swimming movements and musculature of larval herring (Clupea harengus).},
journal = {The Journal of experimental biology},
volume = {110},
number = {},
pages = {217-229},
doi = {10.1242/jeb.110.1.217},
pmid = {6747536},
issn = {0022-0949},
mesh = {Animals ; Fishes/*growth & development/physiology ; Muscle Development ; Swimming ; },
abstract = {A kinematic analysis was made of swimming of larval herring Clupea harengus L. Swimming style was found to change with growth and development; the amplitude of swimming movements of early post-yolk-sac larvae increases linearly towards the tail, a style of swimming which relies mainly on resistive forces for propulsion. Later, after the caudal and dorsal fins have developed, the swimming style changes, in response to an increase in Reynold's Number, such that inertial forces are more important. In this type of swimming the amplitude increases more rapidly than linearly towards the tail. The distribution of red and white muscle fibre types was studied in relation to development. On hatching, red muscle fibres were found to be arranged as a single layer on the outside of the myotomes. They develop into the adult distribution, concentrated at the midline of the flank near the skin, only after the gills and circulation become fully functional.},
}

Animals
Fishes/*growth & development/physiology
Muscle Development
Swimming

@article {pmid6652213,
year = {1983},
author = {Jones, RD and Lemanski, CL and Jones, TJ},
title = {Theory of attachment in Giardia.},
journal = {Biophysical journal},
volume = {44},
number = {2},
pages = {185-190},
pmid = {6652213},
issn = {0006-3495},
mesh = {Adhesiveness ; Giardia/*physiology ; *Models, Biological ; },
abstract = {Using a low Reynold's number hydrodynamic model, the adhesive force in Giardia is calculated. It is shown that this force is larger than typical forces that would tend to detach the organism.},
}

Adhesiveness
Giardia/*physiology
*Models, Biological

@article {pmid7409200,
year = {1980},
author = {Macklem, PT},
title = {The paradoxical nature of pulmonary pressure-flow relationships.},
journal = {Federation proceedings},
volume = {39},
number = {10},
pages = {2755-2758},
pmid = {7409200},
issn = {0014-9446},
mesh = {Animals ; Bronchi/physiology ; Humans ; Lung/*physiology ; Mathematics ; Models, Biological ; Pressure ; Respiration ; Trachea/physiology ; },
abstract = {Most equations proposed to describe pulmonary pressure-flow relationships are inadequate because the "constants" that contain the airway geometry are not, in fact, constant but vary as the distribution of Reynold's number Re varies with flow or gas density. However, even when the normalized pressure drop is plotted against Re (Moody diagram), different relationships are found for different gas mixtures. Thus the normalized pressure drop is a function of one or more variables in addition to Re. As long as this variable or variables remain unknown, the pulmonary pressure-flow relationships will remain paradoxical.},
}

Animals
Bronchi/physiology
Humans
Lung/*physiology
Mathematics
Models, Biological
Pressure
Respiration
Trachea/physiology

@article {pmid508236,
year = {1979},
author = {Fermor, U and Huber, H and Neuhaus, KL and Schmiel, FK and Spiller, P},
title = {Measurement of flow velocity in the model circulation by videodensitometry. Methodological investigations.},
journal = {Basic research in cardiology},
volume = {74},
number = {4},
pages = {361-377},
pmid = {508236},
issn = {0300-8428},
mesh = {*Blood Flow Velocity ; Densitometry/*methods ; *Models, Structural ; *Television ; },
abstract = {The relation between videodensitometrically measured front velocity and electromagnetically assessed flow was examined in a circulatory model with continuous as well as pulsatile flow (89 experiments). The diameter of the tubes in the videodensitometric measuring section was 0.305 to 0.518 cm. A linear correlation was proved in flow velocities up to Reynold's number Re = 225. The exact flow, measured electromagnetically, was overestimated in continuous flow by 21% (r = 0.99, Syx = +/- 14.5 ml/min) and in pulsatile flow by 24% (r = 0.98, Syx = +/- 20.8 ml/min). In view of these results the phasic and average flow can be calculated accurately using videodensitometric techniques.},
}

*Blood Flow Velocity
Densitometry/*methods
*Models, Structural
*Television

@article {pmid608670,
year = {1977},
author = {Nachtigall, W},
title = {[On the significance of Reynold's number and the fluid mechanical phenomena connected to it in swimming physiology and flight biophysics (author's transl)].},
journal = {Fortschritte der Zoologie},
volume = {24},
number = {2-3},
pages = {13-56},
pmid = {608670},
issn = {0071-7991},
mesh = {Animals ; *Biomechanical Phenomena ; *Flight, Animal ; *Locomotion ; Swimming ; },
}

Animals
*Biomechanical Phenomena
*Flight, Animal
*Locomotion
Swimming

@article {pmid39302246,
year = {2024},
author = {Gomez, M and Montalvo, S and Sanchez, A and Conde, D and Ibarra-Mejia, G and Peñailillo, LE and Gurovich, AN},
title = {Effects of Different Eccentric Cycling Intensities on Brachial Artery Endothelial Shear Stress and Blood Flow Patterns.},
journal = {Research quarterly for exercise and sport},
volume = {},
number = {},
pages = {1-11},
doi = {10.1080/02701367.2024.2404139},
pmid = {39302246},
issn = {2168-3824},
abstract = {Eccentric exercise has gained attention as a novel exercise modality that increases muscle performance at a lower metabolic demand. However, vascular responses to eccentric cycling (ECC) are unknown, thus gaining knowledge regarding endothelial shear stress (ESS) during ECC may be crucial for its application in patients. The purpose of this study was to explore ECC-induced blood flow patterns and ESS across three different intensities in ECC. Eighteen young, apparently healthy subjects were recruited for two laboratory visits. Maximum oxygen consumption, power output, and blood lactate (BLa) threshold were measured to determine workload intensities. Blood flow patterns in the brachial artery were measured via ultrasound imaging and Doppler on an eccentric ergometer during a 5 min workload steady exercise test at low (BLa of 0-2 mmol/L), moderate (BLa 2-4 mmol/L), and high intensity (BLa levels > 4 mmol/L). There was a significant increase in the antegrade ESS in an intensity-dependent manner (baseline: 44.2 ± 8.97; low: 55.6 ± 15.2; moderate: 56.0 ± 10.5; high: 70.7 ± 14.9, all dynes/cm2, all p values < 0.0002) with the exception between low and moderate and Re (AU) showed turbulent flow at all intensities. Regarding retrograde flow, ESS also increased in an intensity-dependent manner (baseline 9.72 ± 4.38; low: 12.5 ± 3.93; moderate: 15.8 ± 5.45; high: 15.7 ± 6.55, all dynes/cm2, all p values < 0.015) with the exception between high and moderate and Re (AU) showed laminar flow in all intensities. ECC produced exercise-induced blood flow patterns that are intensity-dependent. This suggests that ECC could be beneficial as a modulator of endothelial homeostasis.},
}

@article {pmid39294953,
year = {2024},
author = {Sznajder, P and Zdybel, P and Liu, L and Ekiel-Jeżewska, ML},
title = {Scaling law for a buckled elastic filament in a shear flow.},
journal = {Physical review. E},
volume = {110},
number = {2-2},
pages = {025104},
doi = {10.1103/PhysRevE.110.025104},
pmid = {39294953},
issn = {2470-0053},
abstract = {We analyze the three-dimensional (3D) buckling of an elastic filament in a shear flow of a viscous fluid at low Reynolds number and high Péclet number. We apply the Euler-Bernoulli beam (elastica) theoretical model. We show the universal character of the full 3D spectral problem for a small perturbation of a thin filament from a straight position of arbitrary orientation. We use the eigenvalues and eigenfunctions for the linearized elastica equation in the shear plane, found earlier by Liu et al. [Phys. Rev. Fluids 9, 014101 (2024)2469-990X10.1103/PhysRevFluids.9.014101] with the Chebyshev spectral collocation method, to solve the full 3D eigenproblem. We provide a simple analytic approximation of the eigenfunctions, represented as Gaussian wave packets. As the main result of the paper, we derive the square-root dependence of the eigenfunction wave number on the parameter χ[over ̃]=-ηsin2ϕsin^{2}�
�, where η is the elastoviscous number and the filament orientation is determined by the zenith angle θ with respect to the vorticity direction and the azimuthal angle ϕ relative to the flow direction. We also compare the eigenfunctions with shapes of slightly buckled elastic filaments with a non-negligible thickness with the same Young's modulus, using the bead model and performing numerical simulations with the precise hydromultipole numerical codes.},
}

@article {pmid39277710,
year = {2024},
author = {Ueki, N and Wakabayashi, KI},
title = {Multicellularity and increasing Reynolds number impact on the evolutionary shift in flash-induced ciliary response in Volvocales.},
journal = {BMC ecology and evolution},
volume = {24},
number = {1},
pages = {119},
pmid = {39277710},
issn = {2730-7182},
mesh = {*Cilia/physiology ; *Biological Evolution ; Chlorophyta/physiology/genetics ; Volvox/genetics/physiology ; Light ; },
abstract = {BACKGROUND: Volvocales in green algae have evolved by multicellularity of Chlamydomonas-like unicellular ancestor. Those with various cell numbers exist, such as unicellular Chlamydomonas, four-celled Tetrabaena, and Volvox species with different cell numbers (~1,000, ~5,000, and ~10,000). Each cell of these organisms shares two cilia and an eyespot, which are used for swimming and photosensing. They are all freshwater microalgae but inhabit different fluid environments: unicellular species live in low Reynolds-number (Re) environments where viscous forces dominate, whereas multicellular species live in relatively higher Re where inertial forces become non-negligible. Despite significant changes in the physical environment, during the evolution of multicellularity, they maintained photobehaviors (i.e., photoshock and phototactic responses), which allows them to survive under changing light conditions.

RESULTS: In this study, we utilized high-speed imaging to observe flash-induced changes in the ciliary beating manner of 27 Volvocales strains. We classified flash-induced ciliary responses in Volvocales into four patterns: "1: temporal waveform conversion", "2: no obvious response", "3: pause in ciliary beating", and "4: temporal changes in ciliary beating directions". We found that which species exhibit which pattern depends on Re, which is associated with the individual size of each species rather than phylogenetic relationships.

CONCLUSIONS: These results suggest that only organisms that acquired different patterns of ciliary responses survived the evolutionary transition to multicellularity with a greater number of cells while maintaining photobehaviors. This study highlights the significance of the Re as a selection pressure in evolution and offers insights for designing propulsion systems in biomimetic micromachines.},
}

*Cilia/physiology
*Biological Evolution
Chlorophyta/physiology/genetics
Volvox/genetics/physiology
Light

@article {pmid39270724,
year = {2024},
author = {Herrera-Amaya, A and Byron, ML},
title = {Propulsive efficiency of spatiotemporally asymmetric oscillating appendages at intermediate Reynolds numbers.},
journal = {Bioinspiration & biomimetics},
volume = {},
number = {},
pages = {},
doi = {10.1088/1748-3190/ad7abf},
pmid = {39270724},
issn = {1748-3190},
abstract = {Many organisms use flexible appendages for locomotion, feeding, and other functional behaviors. The efficacy of these behaviors is determined in large part by the fluid dynamics of the appendage interacting with its environment. For oscillating appendages at low Reynolds numbers, viscosity dominates over inertia, and appendage motion must be spatially asymmetric to generate net flow. At high Reynolds numbers, viscous forces are negligible and appendage motion is often also temporally asymmetric, with a fast power stroke and a slow recovery stroke; such temporal asymmetry does not affect the produced flow at low Reynolds numbers. At intermediate Reynolds numbers, both viscous and inertial forces play non-trivial roles---correspondingly, both spatial and temporal asymmetry can strongly affect overall propulsion. Here we perform experiments on three robotic paddles with different material flexibilities and geometries, allowing us to explore the effects of motion asymmetry (both spatial and temporal) on force production. We show how a flexible paddle's time-varying shape throughout the beat cycle can reorient the direction of the produced force, generating both thrust and lift. We also evaluate the propulsive performance of the paddle by introducing a new quantity, which we term "integrated efficiency". This new definition of propulsive efficiency can be used to directly evaluate an appendage's performance independently from full-body swimming dynamics. Use of the integrated efficiency allows for accurate performance assessment, generalization, and comparison of oscillating appendages in both robotic devices and behaving organisms. Finally, we show that a curved flexible paddle generates thrust more efficiently than a straight paddle, and produces spatially asymmetric motion---thereby improving performance---without the need for complex actuation and controls, opening new avenues for bioinspired technology development.},
}

@article {pmid39269970,
year = {2024},
author = {Hudha, MN and Hasan, MJ and Bairagi, T and Azad, AK and Rahman, MM},
title = {Artificial Neural Network analysis on the effect of mixed convection in triangular-shaped geometry using water-based Al2O3 nanofluid.},
journal = {PloS one},
volume = {19},
number = {9},
pages = {e0304826},
doi = {10.1371/journal.pone.0304826},
pmid = {39269970},
issn = {1932-6203},
mesh = {*Neural Networks, Computer ; *Aluminum Oxide/chemistry ; *Water/chemistry ; *Convection ; Hydrodynamics ; Finite Element Analysis ; },
abstract = {The objective of the study is to investigate the fluid flow and heat transfer characteristics applying Artificial Neural Networks (ANN) analysis in triangular-shaped cavities for the analysis of magnetohydrodynamics (MHD) mixed convection with varying fluid velocity of water/Al2O3 nanofluid. No study has yet been conducted on this geometric configuration incorporating ANN analysis. Therefore, this study analyzes and predicts the complex interactions among fluid flow, heat transfer, and various influencing factors using ANN analysis. The process of finite element analysis was conducted, and the obtained results have been verified by previous literature. The Levenberg-Marquardt backpropagation technique was selected for ANN. Various values of the Richardson number (0.01 ≤ Ri ≤ 5), Hartmann number (0 ≤ Ha ≤ 100), Reynolds number (50 ≤ Re ≤ 200), and solid volume fraction of the nanofluid (ϕ = 1%, 3% and 4%) have been selected. The ANN model incorporates the Gauss-Newton method and the method of damped least squares, making it suitable for tackling complex problems with a high degree of non-linearity and uncertainty. The findings have been shown through the use of streamlines, isotherm plots, Nusselt numbers, and the estimated Nusselt number obtained by ANN. Increasing the solid volume fraction improves the rate of heat transmission for all situations with varying values of Ri, Re, and Ha. The Nusselt number is greater with larger values of the Ri and Re parameters, but it lessens for higher value of Ha. Furthermore, ANN demonstrates exceptional precision, as evidenced by the Mean Squared Error and R values of 1.05200e-6 and 0.999988, respectively.},
}

*Neural Networks, Computer
*Aluminum Oxide/chemistry
*Water/chemistry
*Convection
Hydrodynamics
Finite Element Analysis

@article {pmid39261548,
year = {2024},
author = {Guo, Y and Zou, H and Wei, F and Li, Q and Guo, D and Pirov, J},
title = {Analysis of pedestrian second crossing behavior based on physics-informed neural networks.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {21278},
pmid = {39261548},
issn = {2045-2322},
support = {Z2023178//Undergraduate Education Reform in Shandong Province/ ; M2022179//Undergraduate Education Reform in Shandong Province/ ; 52272343//Foundation for Innovative Research Groups of the National Natural Science Foundation of China/ ; },
abstract = {Pedestrian two-stage crossings are common at large, busy signalized intersections with long crosswalks and high traffic volumes. This design aims to address pedestrian operation and safety by allowing navigation in two stages, negotiating each traffic direction separately. Understanding crosswalk behavior, especially during bidirectional interactions, is essential. This paper presents a two-stage pedestrian crossing model based on Physics-Informed Neural Networks (PINNs), incorporating fluid dynamics equations to determine characteristics such as speed, density, acceleration, and Reynolds number during crossings. The study shows that PINNs outperform traditional deep learning methods in calculating and predicting pedestrian fluid properties, achieving a mean squared error as low as 10[-8]. The model effectively captures dynamic pedestrian flow characteristics and provides insights into pedestrian behavior impacts. The results are significant for designing pedestrian facilities to ensure comfort and optimizing signal timing to enhance mobility and safety. Additionally, these findings can aid autonomous vehicles in better understanding pedestrian intentions in intelligent transportation systems.},
}

@article {pmid39247324,
year = {2024},
author = {Tavakoli, MR and Akbari, OA and Mohammadian, A and Pourfattah, F},
title = {Investigation of the effect of rectangular winglet angles on turbulent flow and heat transfer of water/Cu nanofluid in a three-dimensional channel.},
journal = {Heliyon},
volume = {10},
number = {16},
pages = {e36482},
pmid = {39247324},
issn = {2405-8440},
abstract = {This numerical simulation studies a homogenous and single-phase nanofluid's turbulent flow and heat transfer behavior in a three-dimensional rectangular microchannel. This study's main purpose is to investigate the use of rectangular winglet angles on flow path and its effect on turbulent flow regime and heat transfer parameters. In the current study, the Reynolds number, winglet attack angle (θ), and twisted angle range (α) (or Pitch angle) from 3000 to 12000, 30°≤ θ ≤ 60°, and 15°≤α ≤ 45°, respectively. Also, Cu nanoparticles with volume fractions of 0-4% are used in water as the base fluid. Results of this study show that heat transfer and flow physics of cooling fluid are affected by the variations of attack angle and winglet twist, and the creation of secondary flows leads to the mixture and deviation of flow. A decrease in the attack angle of the winglet causes the creation of strong vortexes and an increase in Nusselt number and heat transfer. In all investigated situations, with the angle of attack constant, increasing the twist angle can improve the Nusselt number between 11 and 18 percent. Also, increasing the angle of attack of the winglet from 30 to 60° can reduce the Nusselt number by 4-8 percent. The results indicate that changing the winglet angle increases the friction coefficient, and at higher Reynolds numbers, this parameter decreases. Also, by increasing Reynolds number, the ratio of friction coefficient to Nusselt number reduces, leading to the decrease of performance evaluation criterion (PEC).},
}

@article {pmid39239773,
year = {2024},
author = {Grigor, E and Carver, J and Bulan, E and Scott, S and Chew, YJ and Perera, S},
title = {A New Generation of Activated Carbon Adsorbent Microstructures.},
journal = {Advanced science (Weinheim, Baden-Wurttemberg, Germany)},
volume = {},
number = {},
pages = {e2406551},
doi = {10.1002/advs.202406551},
pmid = {39239773},
issn = {2198-3844},
support = {//Avon Protection - Melksham, UK, SN12 6NB/ ; //Defence Science and Technology Laboratory - Salisbury, UK, SP4 0JQ/ ; //University of Bath - Bath, UK, BA2 7AY/ ; },
abstract = {This work presents the successful manufacture and characterization of bespoke carbon adsorbent microstructures such as tessellated (TES) or serpentine spiral grooved (SSG) by using 3D direct light printing. This is the first time stereolithographic printing has been used to exert precise control over specific micromixer designs to quantify the impact of channel structure on the removal of n-butane. Activated microstructures achieved nitrogen Brunauer Emmett Teller (BET) surface areas up to 1600 m[2] g[-1] while maintaining uniform channel geometries. When tested with 1000 ppm n-butane at 1 L min[-1], the microstructures exceeded the equilibrium loading of commercial carbon-packed beds by over 40%. Dynamic adsorption breakthrough testing using a constant Reynolds number (Re 80) shows that complex micromixer designs surpassed simpler geometries, with the SSG geometry achieving a 41% longer breakthrough time. Shorter mass transfer zones were observed in all the complex geometries, suggesting superior kinetics and carbon structure utilization as a result of the micromixer-based etched grooves and interlinked channels. Furthermore, pressure drop testing demonstrates that all microstructures had half the pressure drop of commercial carbon-packed beds. This study shows the power of leveraging 3D printing to produce optimized microstructures, providing a glimpse into the future of high-performance gas separation.},
}

@article {pmid39236358,
year = {2024},
author = {Gritti, F and Chen, EY and Datta, SS},
title = {Harnessing an elastic flow instability to improve the kinetic performance of chromatographic columns.},
journal = {Journal of chromatography. A},
volume = {1735},
number = {},
pages = {465326},
doi = {10.1016/j.chroma.2024.465326},
pmid = {39236358},
issn = {1873-3778},
abstract = {Despite decades of research and development, the optimal efficiency of slurry-packed HPLC columns is still hindered by inherent long-range flow heterogeneity from the wall to the central bulk region of these columns. Here, we show an example of how this issue can be addressed through the straightforward addition of a semidilute amount (500 ppm) of a large, flexible, synthetic polymer (18 MDa partially hydrolyzed polyacrylamide, HPAM) to the mobile phase (1% NaCl aqueous solution, hereafter referred to as "brine") during operation of a 4.6 mm × 300 mm column packed with 10μm BEH[TM] 125 Å particles. Addition of the polymer imparts elasticity to the mobile phase, causing the flow in the interparticle pore space to become unstable above a threshold flow rate. We verify the development of this elastic flow instability using pressure drop measurements of the friction factor versus Reynolds number. In prior work, we showed that this flow instability is characterized by large spatiotemporal fluctuations in the pore-scale flow velocities that may promote analyte dispersion across the column. Axial dispersion measurements of the quasi non-retained tracer thiourea confirm this possibility: they reveal that operating above the onset of the instability improves column efficiency by greater than 100%. These experiments thereby suggest that elastic flow instabilities can be harnessed to mitigate the negative impact of trans-column flow heterogeneities on the efficiency of slurry-packed HPLC columns. While this approach has its own inherent limitations and constraints, our results lay the groundwork for future targeted development of polymers that can impart elasticity when dissolved in commonly used liquid chromatography mobile phases, and can thereby generate elastic flow instabilities to help improve the resolution of HPLC columns.},
}

@article {pmid39220585,
year = {2024},
author = {Harte, NC and Obrist, D and Caversaccio, M and Lajoinie, GPR and Wimmer, W},
title = {Transverse flow under oscillating stimulation in helical square ducts with cochlea-like geometrical curvature and torsion.},
journal = {European journal of mechanics. B, Fluids},
volume = {107},
number = {},
pages = {165-174},
pmid = {39220585},
issn = {0997-7546},
abstract = {The cochlea, situated within the inner ear, is a spiral-shaped, liquid-filled organ responsible for hearing. The physiological significance of its shape remains uncertain. Previous research has scarcely addressed the occurrence of transverse flow within the cochlea, particularly in relation to its unique shape. This study aims to investigate the impact of the geometric features of the cochlea on fluid dynamics by characterizing transverse flow induced by harmonically oscillating axial flow in square ducts with curvature and torsion resembling human cochlear anatomy. We examined four geometries to investigate curvature and torsion effects on axial and transverse flow components. Twelve frequencies from 0.125 Hz to 256 Hz were studied, covering infrasound and low-frequency hearing, with mean inlet velocity amplitudes representing levels expected for normal conversation or louder situations. Our simulations show that torsion contributes significantly to transverse flow in unsteady conditions, and that its contribution increases with increasing oscillation frequency. Curvature alone has a small effect on transverse flow strength, which decreases rapidly with increasing frequency. Strikingly, the combined effect of curvature and torsion on transverse flow is greater than expected from a simple superposition of the two effects, especially when the relative contribution of curvature alone becomes negligible. These findings may be relevant to understanding physiological processes in the cochlea, including metabolite transport and wall shear stress. Further studies are needed to investigate possible implications for cochlear mechanics.},
}

@article {pmid39181970,
year = {2024},
author = {Zaman, SU and Hussain, A and Ashraf, K and Sarwar, L and Hussain, F and Altalbe, A and Bekir, A and Muhammad, T},
title = {Mathematical analysis of isothermal study of reverse roll coating using Micropolar fluid.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {19709},
pmid = {39181970},
issn = {2045-2322},
support = {(PSAU/2024/01/921063)//Ali Altalbe/ ; },
abstract = {This article demonstrates a mathematical model and theoretical analysis of the Micropolar fluid in the reverse roll coating process. It is important because micropolar fluids account for the microstructure and microrotation of particles within the fluid. These characteristics are significant for accurately describing the behavior of complex fluids such as polymer solutions, biological fluids, and colloidal suspensions. First, we modeled the flow equations using basic laws of fluid dynamics. The flow equations are made modified using low Reynolds number theory. The simplified equations are solved analytically. The exact expression for velocity and pressure gradient are obtained, while pressure is calculated numerically using Simpson Rule. Graphical depictions are carried out to comprehend the impact of the newly emerged physical constraints. The influence of micropolar and microrotation parameters on the velocity, pressure and pressure gradient are elaborated with the help of different graphs.},
}

@article {pmid39180481,
year = {2024},
author = {Lyons, BM and Maynes, D and Crockett, J and Iverson, BD},
title = {Drop Retention and Departure in Adiabatic Shear Flow on Structured Superhydrophobic Surfaces.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.4c00777},
pmid = {39180481},
issn = {1520-5827},
abstract = {Drops are retained or held on surfaces due to a retention force exerted on the drop by the surface. This retention force is a function of the surface tension of the liquid, drop geometry, and the contact angle between the drop and the surface. When external or body forces exceed the retention force, the drop begins to move. This work explores the conditions for which drop departure occurs on structured superhydrophobic surfaces in the presence of an applied shear flow. Drop departure is explored for five microstructured superhydrophobic surfaces, one nanostructured carbon nanotube surface and one smooth hydrophobic surface. Surface solid fractions range from 0.05 to 1.00, and measured static contact angles range from 121° to 161°. Droplet volumes of 5, 10, 20, 30, 40, and 50 μL are tested on each surface. For each experiment, increasing air velocity is applied to a droplet placed on a surface until the droplet departs. High-speed imaging is used to track droplet base length, height, cross-section area (as viewed from the side) and advancing/receding contact angles. Measurements of drop advancing and receding contact angles are reported at the point of departure, with increasing contact angle hysteresis observed prior to departure. Contact angle hysteresis is observed to be a good indicator of droplet mobility. Measurements of the average air velocity over the height of the droplet are determined at the point of departure for all conditions. The measured air velocity shows strong dependence on the surface solid fraction, and the required shear flow velocity decreases as the surface solid fraction decreases. This is most pronounced at very low solid fractions. A coefficient of drag for the departing drops in shear flow is calculated and is shown to decrease with increasing Reynolds number.},
}

@article {pmid39175794,
year = {2024},
author = {Gerolymos, GA and Vallet, I},
title = {Compressible turbulent plane channel DNS datasets.},
journal = {Data in brief},
volume = {55},
number = {},
pages = {110737},
doi = {10.1016/j.dib.2024.110737},
pmid = {39175794},
issn = {2352-3409},
abstract = {The database contains detailed statistics of compressible turbulent plane channel (TPC) flow, obtained from direct numerical simulation (DNS), with a very-high-order massively parallel solver of the compressible Navier-Stokes equations. It contains datasets for 25 different flow conditions determined by the corresponding HCB friction Reynolds number and centerline Mach number, covering the ranges 100 ⪅ R e τ ★ ⪅ 1000 and 0.3 ⪅ M ¯ CL x ⪅ 2.5 . All calculations are for strictly isothermal wall conditions at temperature T w = 298 K in a medium-size (MB) computational box (8 π δ × 2 δ × 4 π δ where 2 δ is the channel-height). Statistics (moments and pdfs) were collected after the elimination of the transient, and post-processed to create the dataset, which contains only plain text (.txt) space-separated multicolumn files for ease of use. The dataset for each flow-condition is tagged by the values of (R e τ ★ , M ¯ CL x) and is organized in 4 directories: (0) global data files, (1) profiles and budgets (meanflow profiles, velocity-moments up to 6-order, budgets of Reynolds-stresses transport, turbulent fluxes appearing in transport equations for velocity-moments and thermodynamic quantities, correlation coefficients between thermodynamic variables, and skewness and flatness profiles) as a function of the wall-distance, (2) single-variable probability density functions (pdfs) for numerous flow quantities at selected wall-normal distances, and (3) two-variable joint pdfs for numerous couples of flow-quantities at the same selected wall-normal distances.},
}

@article {pmid39170061,
year = {2024},
author = {Morley, EJ and Brockett, CL and Verbruggen, SW},
title = {Analytical and computational studies predict negligible risk of cell death from eddy generation off flat surfaces in cell culture flow systems.},
journal = {Frontiers in bioengineering and biotechnology},
volume = {12},
number = {},
pages = {1340653},
pmid = {39170061},
issn = {2296-4185},
abstract = {Cell-based therapies represent the current frontier of biomedical innovations, with the technologies required underpinning treatments as broad as CAR-T cell therapies, stem cell treatments, genetic therapies and mRNA manufacture. A key bottleneck in the manufacturing process for each of these lies in the expansion of cells within a bioreactor vessel, requiring by far the greatest share of time for what are often time-critical therapies. While various designs, culture feeding and mixing methods are employed in these bioreactors, a common concern among manufacturers and researchers lies in whether shear stresses generated by culture media flow will damage cells and inhibit expansion. This study develops an analytical tool to link macro-scale measures of flow to risk of cell death using relationships with eddy size and dissipation rates, from eddies generated off flat surfaces. This analytical tool was then employed using computational fluid dynamics (CFD) to replicate a range of generic bioreactor geometries and flow conditions. We found that no combination of flow condition or design parameter was predicted by the tool to cause cell death within eddies, indicating negligible risk of cell death due to eddy formation within cell culture systems. While this requires experimental validation, and does not apply when cells are expanded using microcarriers, this tool nonetheless provides reassurance and accessible prediction of bioreactor design parameters that could result in cell death. Finally, our findings show that bioreactor design can be tailored such that the shear stress stimulation of cells can be selectively altered through small changes in flow rate.},
}

@article {pmid39166020,
year = {2024},
author = {Ahmadi Azar, A and Jalili, P and Poolaei Moziraji, Z and Jalili, B and Domiri Ganji, D},
title = {Analytical solution for MHD nanofluid flow over a porous wedge with melting heat transfer.},
journal = {Heliyon},
volume = {10},
number = {15},
pages = {e34888},
pmid = {39166020},
issn = {2405-8440},
abstract = {This study employs the Hybrid Analytical-Numerical (HAN) method to investigate steady two-dimensional magnetohydrodynamic (MHD) nanofluid flow over a permeable wedge. Analyzing hyperbolic tangent nanofluid flow, the governing time-independent partial differential equations (PDEs) for continuity, momentum, energy, and concentration transform into a set of nonlinear third-order coupled ordinary differential equations (ODEs) through similarity transformations. These ODEs encompass critical parameters such as Lewis and Prandtl numbers, Brownian diffusion, Weissenberg number, thermophoresis, Dufour and Soret numbers, magnetic field strength, thermal radiation, power law index, and medium permeability. The study explores how variations in these parameters impact the velocity field, skin friction coefficient, Nusselt, and Sherwood numbers. Noteworthy findings include the sensitivity of fluid velocity to parameters like Weissenberg number, power law index, wedge angle, magnetic field strength, permeability, and melting heat transfer. The skin friction coefficient experiences a significant increase with specific parameter changes, while Nusselt and Sherwood numbers remain relatively constant. The local Reynolds number significantly affects Nusselt and Sherwood numbers, with a less pronounced impact on the skin friction coefficient. The study's uniqueness lies in employing the analytical HAN method and extracting recent insights from the results.},
}

@article {pmid39165174,
year = {2024},
author = {Liu, Y and Zhang, J and Peng, X and Yan, S},
title = {Deciphering the Evolution of Inertial Migration in Serpentine Channels.},
journal = {Analytical chemistry},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.analchem.4c03474},
pmid = {39165174},
issn = {1520-6882},
abstract = {Serpentine channels coupling inertial and secondary flows enable effective particle focusing and separation, showing great potential in clinical diagnostics and drug screening. However, the nonsteady secondary flows in the serpentine channel make the evolution of inertial migration unclear, hindering the development and application of the serpentine channel. Herein, to refine the inertial migration mechanism, we established a model with varying curvature ratios to study the effect of secondary flow on particle migration in the serpentine channel. This method used direct numerical simulation (DNS) to calculate inertial lift, mapped the inertial lift to cross sections of the serpentine channel, and deciphered the inertial migration by using the Lagrangian particle tracking (LPT) method. The inertial migration of microparticles is experimentally investigated to validate the established numerical model. The results indicate that particle migration in serpentine channels follows a two-stage migration. An increase in secondary flow accelerates the second stage of the migration process while slowing the first stage process. Subsequently, we investigated the effects of different parameters, including Reynolds number, aspect ratio, and blockage ratio, on the equilibrium positions of particles, providing guidelines for the high-resolution separation of particles. Taking flow resistance into account, the dimensionless study makes the separation of arbitrary-sized particles possible. This work reveals the migration mechanism in serpentine channels, paving the way for the inertial separation of the particles.},
}

@article {pmid39160957,
year = {2024},
author = {Zigelman, A and Ben Zvi, G and Or, Y},
title = {Dynamics of Purcell-type microswimmers with active-elastic joints.},
journal = {Physical review. E},
volume = {110},
number = {1-1},
pages = {014207},
doi = {10.1103/PhysRevE.110.014207},
pmid = {39160957},
issn = {2470-0053},
abstract = {Purcell's planar three-link microswimmer is a classic model of swimming in low-Reynolds-number fluid, inspired by motion of flagellated microorganisms. Many works analyzed this model, assuming that the two joint angles are directly prescribed in phase-shifted periodic inputs. In this work, we study a more realistic scenario by considering an extension of this model which accounts for joints' elasticity and mechanical actuation of periodic torques so that the joint angles are dynamically evolving. Numerical analysis of the swimmer's dynamics reveals multiplicity of periodic solutions, depending on parameters of the inputs-frequency and amplitude of excitation, joints' stiffness ratio, as well as joint's activation. We numerically study swimming direction reversal, as well as bifurcations, stability transitions, and symmetry breaking of the periodic solutions, which represent the effect of buckling instability observed in swimming microorganisms. The results demonstrate that this variant of Purcell's simple model displays rich nonlinear dynamic behavior with actuated-elastic joints. Similar results are also obtained when studying an extended model of a six-link microswimmer.},
}

@article {pmid39160917,
year = {2024},
author = {Puggioni, L and Musacchio, S},
title = {Orientational order and topological defects in a dilute solutions of rodlike polymers at low Reynolds number.},
journal = {Physical review. E},
volume = {110},
number = {1-2},
pages = {015104},
doi = {10.1103/PhysRevE.110.015104},
pmid = {39160917},
issn = {2470-0053},
abstract = {The relationship between the polymer orientation and the chaotic flow, in a dilute solution of rigid rodlike polymers at low Reynolds number, is investigated by means of direct numerical simulations. It is found that the rods tend to align with the velocity field in order to minimize the friction with the solvent fluid, while regions of rotational disorder are related to strong vorticity gradients, and therefore to the chaotic flow. The "turbulent-like" behavior of the system is therefore associated with the emergence and interaction of topological defects of the mean director field, similarly to active nematic turbulence. The analysis has been carried out in both two and three spatial dimensions.},
}

@article {pmid39140230,
year = {2024},
author = {Mohammadali, R and Bayareh, M and Nadooshan, AA},
title = {Performance optimization of a DLD microfluidic device for separating deformable CTCs.},
journal = {Electrophoresis},
volume = {},
number = {},
pages = {},
doi = {10.1002/elps.202400136},
pmid = {39140230},
issn = {1522-2683},
abstract = {Deterministic lateral displacement (DLD) microfluidic devices work based on the streamlines created by an array of micro-posts. The configuration of pillars alters the isolation efficiency of these devices. The present paper optimizes the performance of a DLD device for isolating deformable circulating tumor cells. The input variables include cell diameter (d), Young's modulus (E s ${E}_
s$), Reynolds number (Re), and tan θ, where θ is the tilted angle of micro-posts. The output, which is the response of the system, is DLD. The numerical simulation results are employed to optimize the device using the response surface method, leading to the proposition of a correlation to estimate DLD as a function of input variables. It is demonstrated that the maximum and minimum impacts on cell lateral displacement correspond to E s ${E}_
s$ and Re, respectively.},
}

@article {pmid39138284,
year = {2024},
author = {Nagalingam, N and Korede, V and Irimia, D and Westerweel, J and Padding, JT and Hartkamp, R and Eral, HB},
title = {Unified framework for laser-induced transient bubble dynamics within microchannels.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {18763},
pmid = {39138284},
issn = {2045-2322},
support = {16714//Nederlandse Organisatie voor Wetenschappelijk Onderzoek/ ; },
abstract = {Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied-a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows (< 1000), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation.},
}

@article {pmid39130567,
year = {2024},
author = {Miah, MAK and Ahasan, K and Kingston, TA and Olsen, MG and Juárez, JJ},
title = {Microscopic Particle Image Velocimetry Analysis of Multiphase Flow in a Porous Media Micromodel.},
journal = {ACS omega},
volume = {9},
number = {31},
pages = {34070-34080},
pmid = {39130567},
issn = {2470-1343},
abstract = {Pore-scale oil displacement behavior was investigated in a porous media micromodel using microscopic particle image velocimetry (μPIV). Porous media micromodels consisting of an ordered square array of cylindrical pillars with 50 and 70% porosities were fabricated with photolithography. The oil displacement was performed with the injection of water at flow rates of 37.5, 75, and 150 μL/h. These flow rates correspond to Reynolds number of 1.1 × 10[-2], 2.2 × 10[-2], and 4.4 × 10[-2], respectively in the 50% porous channel, and 1.84 × 10[-3], 3.69 × 10[-3], and 7.38 × 10[-3], respectively in the 70% porous channel. The capillary numbers for these flow rates are 2.18 × 10[-5], 4.36 × 10[-5], and 8.72 × 10[-5], respectively in the 50% porous channel, and 1.56 × 10[-5], 3.12 × 10[-5], and 6.23 × 10[-5], respectively in the 70% porous channel. The micromodel is initially saturated with oil, with the invading water phase following the path of least resistance as it displaces the oil. The μPIV data were used to construct probability density functions (PDFs) which show an initial, nonzero, peak in transverse velocity as the water enters the micromodel. The PDFs broaden with time, indicating that the water is spreading, before retracting to a peak velocity of 0 mm/s, indicating that the water displacement has achieved equilibrium. We developed a model based on conservation of mass to describe the efficiency of the displacement process. All flow conditions demonstrate peak displacement efficiency when the amount of oil phase displacement is ∼9 pore volumes in 50% porous channel and ∼4 pore volumes in 70% porous channel.},
}

@article {pmid39130463,
year = {2024},
author = {Akhter, R and Ali, MM and Alim, MA},
title = {Data analysis of thermal performance and irreversibility of convective flow in porous-wavy channel having triangular obstacle under magnetic field effect.},
journal = {Heliyon},
volume = {10},
number = {14},
pages = {e34580},
pmid = {39130463},
issn = {2405-8440},
abstract = {Mixed convective nanofluid flow has substantial importance in improvement of thermal performance, and thermal engineering to meet the global energy crisis. In this study, mixed convective nanofluid flow in a porous-wavy channel with an inner heated triangular obstacle under magnetic field effect is numerically examined. Nanofluid within the channel is heated and cooled from its bottom and top wavy-surfaces. A heated triangular cylinder is located at the centerline of the wavy-channel. Finite element method is utilized to solve the non-dimensional governing equations. The code is validated comparing present results with published numerical and experimental results. The response surface method is also implemented to analyze the obtained results and its sensitivity. The numerical results indicate that strength of flow velocity is accelerated with rising Reynolds number, Darcy numbers and inlet-outlet ports length but declined for Hartmann number and volume fraction. Heat transferring rate and heat transfer irreversibility are substantially increased for higher values of Reynolds number, inlet-outlet ports length, Darcy number and nanoparticle volume fraction but a reverse trend is occurred for magnetic field effect. The thermal performance is found significantly improved with simultaneous increment in Re, ϕ, Da and decrement in Ha. Positive sensitivity is achieved for input factors Re, ϕ, Da in computing N u a v while negative sensitivity to Ha. Heat transfer rate is found more sensitive to the impact of Re and ϕ compared to Da and Ha. 45.59 % more heat transmission potentiality is developed for using Al2O3-H2O nanofluid (vol.5 %) instead of using base fluid water. Heat transfer enhancement rate is decreased by 36.22 % due to impact of magnetic field strength. In addition, 84.12 % more heat transferring rate is recorded in presence of triangular obstacle. Moreover, irreversibility components are influenced significantly for the presence of heated triangular obstacle. Bejan number is also found declined for increasing physical parameters. The findings of this investigation may offer a guideline for finding experimental results to design high-performance convective heat exchangers.},
}

@article {pmid39124977,
year = {2024},
author = {Chou, YF and Keh, HJ},
title = {Axisymmetric Slow Rotation of Coaxial Soft/Porous Spheres.},
journal = {Molecules (Basel, Switzerland)},
volume = {29},
number = {15},
pages = {},
doi = {10.3390/molecules29153573},
pmid = {39124977},
issn = {1420-3049},
support = {MOST 110-2221-E-002-017-MY3//National Science and Technology Council Taiwan/ ; },
abstract = {The steady low-Reynolds-number rotation of a chain of coaxial soft spheres (each with an impermeable hard core covered by a permeable porous layer) about the axis in a viscous fluid is analyzed. The particles may be unequally spaced, and may differ in the permeability and inner and outer radii of the porous surface layer as well as angular velocity. By using a method of boundary collocation, the Stokes and Brinkman equations for the external fluid flow and flow within the surface layers, respectively, are solved semi-analytically. The particle interaction effect increases as the relative gap thickness between adjacent particles or their permeability decreases, which can be significant as the gap thickness approaches zero. A particle's hydrodynamic torque is reduced (its rotation is enhanced) when other particles rotate in the same direction at equivalent or greater angular velocities, but increases (its rotation is hindered) when other particles rotate in the opposite direction at arbitrary angular velocities. For particles with different radii or permeabilities, the particle interaction has a greater effect on smaller or more permeable particles than on larger or less permeable particles. For the rotation of three particles, the presence of the third particle can significantly affect the hydrodynamic torques acting on the other two particles. For the rotation of numerous particles, shielding effects between particles can be substantial. When the permeability of porous layers is low, relative fluid motion is barely felt by the hard cores of the soft particles. The insights gained from this analysis on the effects of interactions among rotating soft particles may be of great importance in many physicochemical applications of colloidal suspensions.},
}

@article {pmid39110849,
year = {2024},
author = {Zhang, L and Wan, X and Zhou, X and Cao, Y and Duan, H and Yan, J and Li, H and Lv, P},
title = {Pyramid-Shaped Superhydrophobic Surfaces for Underwater Drag Reduction.},
journal = {ACS applied materials & interfaces},
volume = {},
number = {},
pages = {},
doi = {10.1021/acsami.4c09631},
pmid = {39110849},
issn = {1944-8252},
abstract = {Superhydrophobic surfaces hold immense potential in underwater drag reduction. However, as the Reynolds number increases, the drag reduction rate decreases, and it may even lead to a drag increase. The reason lies in the collapse of the air mattress. To address this issue, this paper develops a pyramid-shaped robust superhydrophobic surface with wedged microgrooves, which exhibits a high gas fraction when immersed underwater and good ability to achieve complete spreading and recovery of the air mattress through air replenishment in the case of collapse of the air mattress. Pressure drop tests in a water tunnel confirm that with continuous air injection, the drag reduction reaches 64.8% in laminar flow conditions, substantially greater than 38.4% in the case without air injection, and can achieve 50.8% drag reduction in turbulent flow. This result highlights the potential applications of superhydrophobic surfaces with air mattress recovery for drag reduction.},
}

@article {pmid39103401,
year = {2024},
author = {Refaie Ali, A and Abbasi, WS and Bibi, B and Rahman, H and Ul Islam, S and Hussain Majeed, A and Ahmad, I},
title = {Spacing effects on flows around two square cylinders in staggered arrangement via LBM.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {18049},
pmid = {39103401},
issn = {2045-2322},
abstract = {This study presents a computational analysis of fluid flow characteristics around two staggered arranged square cylinders using the Lattice Boltzmann Method (LBM). With Reynolds number (Re) fixed at 200, numerical simulations explore the influence of varying gap ratios (G) ranging from 0 to 10 times the cylinder size. Emphasis is placed on understanding the impact of cylinders spacing on flow structure mechanisms and induced forces. Investigation of fluid flow parameters includes vorticity behavior, pressure streamlines, and variations in drag and lift coefficients alongside the Strouhal number under different values of G. From the results, four distinct flow patterns emerge: single bluff body flow, flip flopping flow, modulated synchronized flow, and synchronized flow, each exhibiting unique characteristics. This study reveals the strong dependence of fluid forces on G, with low spacing values leading to complex vortex structures and fluctuating forces influenced by jet flow effects. At higher spacing values, proximity effects between cylinders diminish, resulting in a smoother periodic flow. The Strouhal number, average drag force and the rms values of drag and lift force coefficients vary abruptly at narrow gaps and become smooth at higher gap ratios. Unlike the tandem and side-by-side arrangements the staggered cylinders arrangement is found to have significant impact on the pressure variations around both cylinders. Overall, this research could contribute to a comprehensive understanding of staggered cylinder arrangements and their implications for engineering applications.},
}

@article {pmid39102543,
year = {2024},
author = {Saito, M and Arai, F and Yamanishi, Y and Sakuma, S},
title = {Spatiotemporally controlled microvortices provide advanced microfluidic components.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {33},
pages = {e2306182121},
doi = {10.1073/pnas.2306182121},
pmid = {39102543},
issn = {1091-6490},
support = {22J23814//MEXT | Japan Society for the Promotion of Science (JSPS)/ ; JPMJFR2157//MEXT | JST | Fusion Oriented REsearch for disruptive Science and Technology (FOREST)/ ; },
abstract = {Microvortices are emerging components that impart functionality to microchannels by exploiting inertia effects such as high shear stress, effective fluid diffusion, and large pressure loss. Exploring the dynamic generation of vortices further expands the scope of microfluidic applications, including cell stimulation, fluid mixing, and transport. Despite the crucial role of vortices' development within sub-millisecond timescales, previous studies in microfluidics did not explore the modulation of the Reynolds number (Re) in the range of several hundred. In this study, we modulated high-speed flows (54 < [Formula: see text] < 456) within sub-millisecond timescales using a piezo-driven on-chip membrane pump. By applying this method to microchannels with asymmetric geometries, we successfully controlled the spatiotemporal development of vortices, adjusting their behavior in response to oscillatory flow directions. These different vortices induced different pressure losses, imparting the microchannels with direction-dependent flow resistance, mimicking a diode-like behavior. Through precise control of vortex development, we managed to regulate this direction-dependent resistance, enabling the rectification of oscillatory flow resembling a diode and the ability to switch its rectification direction. This component facilitated bidirectional flow control without the need for mechanical valves. Moreover, we demonstrated its application in microfluidic cell pipetting, enabling the isolation of single cells. Consequently, based on modulating high-speed flow, our approach offers precise control over the spatiotemporal development of vortices in microstructures, thereby introducing innovative microfluidic functionalities.},
}

@article {pmid39093039,
year = {2024},
author = {Van Blitterswyk, J and Rocha, J},
title = {Erratum: An experimental study of the wall-pressure fluctuations beneath low Reynolds number turbulent boundary layers [J. Acoust. Soc. Am. 141, 1257-1268 (2017)].},
journal = {The Journal of the Acoustical Society of America},
volume = {156},
number = {2},
pages = {725},
doi = {10.1121/10.0028125},
pmid = {39093039},
issn = {1520-8524},
}

@article {pmid39082012,
year = {2024},
author = {Fahad, MK and Hasan, MJ and Ifraj, NF and Chandra Dey, D},
title = {Numerical investigation on the impact of different design arrangements of helical heat exchangers with varying cross-sections utilizing ternary hybrid nanofluids.},
journal = {Heliyon},
volume = {10},
number = {14},
pages = {e34481},
doi = {10.1016/j.heliyon.2024.e34481},
pmid = {39082012},
issn = {2405-8440},
abstract = {Helical tube heat exchangers (HTHE) are commonly used as thermal devices in various thermal engineering applications. A comparative investigation was undertaken to examine several helical tube designs in relation to their potential uses with water and nanofluids. Additionally, employing the ternary hybrid nanofluid (THNF) flow in helical-type heat exchangers to assess the heat transfer and frictional loss is a unique concept, as there is currently no research on this specific application. This study involves analyzing three different design configurations, each of which has three different inlet profiles: round, square, and oval shapes. Hence, a numerical analysis has been conducted on nine cases, each including the same pipe length, helix diameter, and pitch distance. The specified range for the Reynolds number under the water and THNF flow condition is 5000-25000. The results are acquired for both fluids, considering the Nusselt number (Nu), friction factor (f), outlet temperature (T out), and entropy production (S g). Multi-Criteria Decision Making (MCDM) is employed to provide a thorough assessment of the overall performance of the proposed designs. The results have been shown as graphical representations, streamlines and contours where Nusselt number, friction factor and entropy generation have been evaluated. The Nusselt number has a higher value for the oval cross-section, while it reaches its lowest value for the square cross-section. The highest heat transfer rate is got for Design 1 with the oval-shaped case. The friction factor for a circular cross-section HHTE is 48 % higher than the friction factor for a square cross-section profile. In addition, the square shape at a Reynolds number (Re) of 25000 exhibits 5 % less entropy formation compared to the oval shape geometry at a Reynolds number of 5000. The results of MCDM analysis indicate that Design 1, which features a square section, exhibits superior performance. Conversely, Design 2, which incorporates a circular cross-section, demonstrates poor performance. Among the six ternary hybrid nanofluids, the Al2O3+CNT+Graphene nanofluid with a water basis exhibits the greatest Nusselt number.},
}

@article {pmid39064393,
year = {2024},
author = {Qing, Y and Wang, J and Li, F},
title = {Electro-Osmotic Flow and Mass Transfer through a Rough Microchannel with a Modulated Charged Surface.},
journal = {Micromachines},
volume = {15},
number = {7},
pages = {},
doi = {10.3390/mi15070882},
pmid = {39064393},
issn = {2072-666X},
support = {11902164//The National Natural Science Foundation of China/ ; },
abstract = {In this paper, we investigate the electro-osmotic flow (EOF) and mass transfer of a Newtonian fluid propelled by a pressure gradient and alternating current (AC) electric field in a parallel microchannel with sinusoidal roughness and modulated charged surfaces. The two-wall roughness is described by in-phase or out-of-phase sine functions with a small amplitude δ. By employing the method of perturbation expansion, the semi-analytical solutions of the Poisson-Boltzmann (P-B) equation based on the Debye-Hückel approximation and the modified Navier-Stokes (N-S) equation are obtained. The numerical solution of the concentration equation is obtained by the finite difference method. The effects of sinusoidal roughness, modulated charged surface, and the AC electric field on the potential field, velocity field, and concentration field are discussed. Under the influence of the modulated charged surface and sinusoidal roughness, vortices are generated. The velocity oscillates due to the effect of the AC electric field. The results indicate that solute diffusion becomes enhanced when the oscillation Reynolds number is below a specific critical value, and it slows down when the oscillation Reynolds number exceeds this critical value.},
}

@article {pmid39056856,
year = {2024},
author = {Chen, D and Zhang, B and Zhang, H and Shangguan, Z and Sun, C and Cui, X and Liu, X and Zhao, Z and Liu, G and Chen, H},
title = {Laser Ablating Biomimetic Periodic Array Fish Scale Surface for Drag Reduction.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {7},
pages = {},
doi = {10.3390/biomimetics9070415},
pmid = {39056856},
issn = {2313-7673},
support = {52305311, 52205297, 51935001, 51725501, and T2121003//National Natural Science Foundation of China/ ; ZR2023QE018//Shandong Provincial Natural Science Foundation/ ; },
abstract = {Reducing resistance to surface friction is challenging in the field of engineering. Natural biological systems have evolved unique functional surfaces or special physiological functions to adapt to their complex environments over centuries. Among these biological wonders, fish, one of the oldest in the vertebrate group, have garnered attention due to their exceptional fluid dynamics capabilities. Fish skin has inspired innovation in reducing surface friction due to its unique structures and material properties. Herein, drawing inspiration from the unique properties of fish scales, a periodic array of fish scales was fabricated by laser ablation on a polished aluminum template. The morphology of the biomimetic fish scale surface was characterized using scanning electron microscopy and a white-light interfering profilometer. Drag reduction performance was measured in a closed circulating water tunnel. The maximum drag reduction was 10.26% at a Reynolds number of 39,532, and the drag reduction performance gradually decreased with an increase in the distance between fish scales. The mechanism of the biomimetic drag reduction surface was analyzed using computational fluid dynamics. Streamwise vortices were generated at the valley of the biomimetic fish scale, replacing sliding friction with rolling friction. These results are expected to provide a foundation for in-depth analysis of the hydrodynamic performance of fish and serve as new inspiration for drag reduction and antifouling.},
}

@article {pmid39036949,
year = {2024},
author = {Raihan, MK and Kim, N and Song, Y and Xuan, X},
title = {Elasto-inertial instabilities in the merging flow of viscoelastic fluids.},
journal = {Soft matter},
volume = {},
number = {},
pages = {},
doi = {10.1039/d4sm00743c},
pmid = {39036949},
issn = {1744-6848},
abstract = {Many engineering and natural phenomena involve the merging of two fluid streams through a T-junction. Previous studies of such merging flows have been focused primarily upon Newtonian fluids. We observed in our recent experiment with five different polymer solutions a direct change from an undisturbed to either a steady vortical or unsteady three-dimensional flow at the T-junction with increasing inertia. The transition state(s) in between these two types of merging flow patterns is, however, yet to be known. We present here a systematic experimental study of the merging flow of polyethylene oxide (PEO) solutions with varying polymer concentrations and molecular weights. Two new paths of flow development are identified with the increase of Reynolds number: one is the transition in very weakly viscoelastic fluids first to steady vortical flow and then to a juxtaposition state with an unsteady elastic eddy zone in the middle and a steady inertial vortex on each side, and the other is the transition in weakly viscoelastic fluids first to a steady vortical and/or a juxtaposition state and then to a fully unsteady flow. Interestingly, the threshold Reynolds number for the onset of elastic instabilities in the merging flow is not a monotonic function of the elasticity number, but instead follows a power-law dependence on the polymer concentration relative to its overlap value. Such a dependence turns out qualitatively consistent with the prediction of the McKinley-Pakdel criterion.},
}

@article {pmid39027729,
year = {2024},
author = {Arshi, S and Madane, K and Shortall, K and Hailo, G and Alvarez-Malmagro, J and Xiao, X and Szymanńska, K and Belochapkine, S and Ranade, VV and Magner, E},
title = {Controlled Delivery of H2O2: A Three-Enzyme Cascade Flow Reactor for Peroxidase-Catalyzed Reactions.},
journal = {ACS sustainable chemistry & engineering},
volume = {12},
number = {28},
pages = {10555-10566},
doi = {10.1021/acssuschemeng.4c03220},
pmid = {39027729},
issn = {2168-0485},
abstract = {Peroxidases are promising catalysts for oxidation reactions, yet their practical utility has been hindered by the fact that they require hydrogen peroxide (H2O2), which at high concentrations can cause deactivation of enzymes. Practical processes involving the use of peroxidases require the frequent addition of low concentrations of H2O2. In situ generation of H2O2 can be achieved using oxidase-type enzymes. In this study, a three-enzyme cascade system comprised of a H2O2 generator (glucose oxidase (GOx)), H2O2-dependent enzymes (chloroperoxidase (CPO) or horseradish peroxidase (HRP)), and a H2O2 scavenger (catalase (CAT)) was deployed in a flow reactor. Immobilization of the enzymes on a graphite rod was achieved through electrochemically driven physical adsorption, followed by cross-linking with glutaraldehyde. Modeling studies indicated that the flow in the reactor was laminar (Reynolds number, R e < 2000) and was nearly fully developed at the midplane of the annular reactor. Immobilized CAT and GOx displayed good stability, retaining 79% and 84% of their initial activity, respectively, after three cycles of operation. Conversely, immobilized CPO exhibited a considerable reduction in activity after one use, retaining only 30% of its initial activity. The GOx-CAT-GRE system enabled controlled delivery of H2O2 in a more stable manner with a 4-fold enhancement in the oxidation of indole compared to the direct addition of H2O2. Using CPO in solution coupled with GOx-CAT-GRE yields of 90% for the oxidation of indole to 2-oxyindole and of 93% and 91% for the chlorination of thymol and carvacrol, respectively.},
}

@article {pmid39025780,
year = {2024},
author = {Ashikhmin, A and Piskunov, M and Kochkin, D and Ronshin, F and Chen, L},
title = {Droplet Microfluidic Method for Estimating the Dynamic Interfacial Tension of Ion-Crosslinked Sodium Alginate Microspheres.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.4c01940},
pmid = {39025780},
issn = {1520-5827},
abstract = {The research focuses on optimizing the production of hydrogel microspheres using droplet microfluidics for pharmaceutical and bioengineering applications. A semiempirical method has been developed to predict the dynamic interfacial tension at the interface of ion-cross-linked sodium alginate microsphere-sunflower oil modified with glacial acetic acid and Tween 80 surfactant. These microspheres are produced in a small-scale coaxial device that is manufactured using affordable DLP/LCD 3D printing technology with a transparent photopolymer. The method was tested to design the minireactor in the device, which allows for the production of fully cross-linked microspheres that are ready for use at the output of the reactor without additional cross-linking steps in the microsphere collector. The mathematical expression for estimating the interfacial tension at the moment of formation of a hydrogel microsphere includes the Reynolds number for a two-phase liquid, the Ohnesorge number, and the surface tension at the liquid-air interface for continuous medium flow (modified oil). The reliability of the prediction is confirmed for continuous medium and dispersed phase flow rates of 0.8-3.2 and 0.01-0.08 mL/min, respectively. The evolution of the interfacial tension from the moment the microspheres formed and the estimated ultimate interfacial tension in a cross-linked hydrogel-modified oil system contributed to the reliable determination of the linear size of a minireactor. The ultimate interfacial tension of 76.5 ± 0.3 mN/m was determined using the Young-Laplace equation, which is based on measuring the surface free energy of the hydrogel as soft matter using the Owens-Wendt method. Additionally, the equilibrium static contact angle of the fully cross-linked hydrogel surface wetted with oil is measured using the sessile drop method. From a practical perspective, a method for optimizing and streamlining the high-tech manufacturing of cross-linked polymer microspheres and mini- and microchannel devices for use in bioengineering and pharmaceutical applications is suggested.},
}

@article {pmid39020933,
year = {2024},
author = {Sudarsanan, S and Roy, A and Pavithran, I and Tandon, S and Sujith, RI},
title = {Emergence of order from chaos through a continuous phase transition in a turbulent reactive flow system.},
journal = {Physical review. E},
volume = {109},
number = {6-1},
pages = {064214},
doi = {10.1103/PhysRevE.109.064214},
pmid = {39020933},
issn = {2470-0053},
abstract = {As the Reynolds number is increased, a laminar fluid flow becomes turbulent, and the range of time and length scales associated with the flow increases. Yet, in a turbulent reactive flow system, as we increase the Reynolds number, we observe the emergence of a single dominant timescale in the acoustic pressure fluctuations, as indicated by its loss of multifractality. Such emergence of order from chaos is intriguing. We perform experiments in a turbulent reactive flow system consisting of flame, acoustic, and hydrodynamic subsystems interacting nonlinearly. We study the evolution of short-time correlated dynamics between the acoustic field and the flame in the spatiotemporal domain of the system. The order parameter, defined as the fraction of the correlated dynamics, increases gradually from zero to one. We find that the susceptibility of the order parameter, correlation length, and correlation time diverge at a critical point between chaos and order. Our results show that the observed emergence of order from chaos is a continuous phase transition. Moreover, we provide experimental evidence that the critical exponents characterizing this transition fall in the universality class of directed percolation. Our paper demonstrates how a real-world complex, nonequilibrium turbulent reactive flow system exhibits universal behavior near a critical point.},
}

@article {pmid39020875,
year = {2024},
author = {Samanta, A},
title = {Insights on phase speed and the critical Reynolds number of falling films.},
journal = {Physical review. E},
volume = {109},
number = {6-2},
pages = {065103},
doi = {10.1103/PhysRevE.109.065103},
pmid = {39020875},
issn = {2470-0053},
abstract = {We revisit the studies of gravity-driven viscous falling films with and without imposed shear stress to provide new perspectives on phase speed and the critical Reynolds number for surface instability. We use the traditional long-wave expansion technique implemented for investigating the linear stability analysis [C. S. Yih, Phys. Fluids 6, 321 (1963)0031-917110.1063/1.1706737]. The principal purpose is to create a unified relationship between the leading-order phase speed and the critical Reynolds number that will hold for falling films on impermeable substrates with or without shear stress acting at the liquid film surface. The analytical result demonstrates that the critical Reynolds number for the onset of surface instability is [5/(2c_{0})
]cotθ, where c_{0}
is the leading-order phase speed of the surface mode and θ is the angle of inclination with the horizontal. Clearly, the critical Reynolds number of the surface mode is explicitly dependent on the leading-order phase speed. Furthermore, we reveal that the basic parallel flow with or without imposed shear stress is linearly unstable to infinitesimal disturbances if the modified Reynolds number, Re_{M}=
(Rec_{0}/
cotθ)[ReistheReynoldsnumber,andθ≠π/2], is greater than its critical value of 5/2, which is independent of the shear stress applied at the film surface. In addition, it is demonstrated that Re_{M}
controls the surface instability in the long-wave regime for both shear-imposed and non-shear-imposed film flows.},
}

@article {pmid39009602,
year = {2024},
author = {Kheirkhah Barzoki, A},
title = {Optimization of passive micromixers: effects of pillar configuration and gaps on mixing efficiency.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {16245},
pmid = {39009602},
issn = {2045-2322},
abstract = {Chemical bioreactions play a significant role in many of the microfluidic devices, and their applications in biomedical science have seen substantial growth. Given that effective mixing is vital for initiating biochemical reactions in many applications, micromixers have become increasingly prevalent for high-throughput assays. In this research, a numerical study using the finite element method was conducted to examine the fluid flow and mass transfer characteristics in novel micromixers featuring an array of pillars. The study utilized two-dimensional geometries. The impact of pillar configuration on mixing performance was evaluated using concentration distribution and mixing index as key metrics. The study explores the effects of pillar array design on mixing performance and pressure drop, drawing from principles such as contraction-expansion and split-recombine. Two configurations of pillar arrays, slanted and arrowhead, are introduced, each undergoing investigation regarding parameters such as pillar diameter, gap size between pillar groups, distance between pillars, and vertical shift in pillar groups. Subsequently, optimal micromixers are identified, exhibiting mixing efficiency exceeding 99.7% at moderate Reynolds number (Re = 1), a level typically challenging for micromixers to attain high mixing efficiency. Notably, the pressure drop remains low at 1102 Pa. Furthermore, the variations in mixing index over time and across different positions along the channel are examined. Both configurations demonstrate short mixing lengths and times. At a distance of 4300 μm from the inlet, the slanted and arrowhead configurations yielded mixing indices of 97.2% and 98.9%, respectively. The micromixers could provide a mixing index of 99.5% at the channel's end within 8 s. Additionally, both configurations exceeded 90% mixing indices by the 3 s. The combination of rapid mixing, low pressure drop, and short mixing length positions the novel micromixers as highly promising for microfluidic applications.},
}

@article {pmid38994047,
year = {2024},
author = {Aziz, MA and Gaheen, OA and Benini, E and Elsayed, AM},
title = {Experimental investigation of multi-step airfoils in low Reynolds numbers applications.},
journal = {Heliyon},
volume = {10},
number = {12},
pages = {e32919},
doi = {10.1016/j.heliyon.2024.e32919},
pmid = {38994047},
issn = {2405-8440},
abstract = {This study provides a detailed analysis of the aerodynamic performance of various airfoil configurations, focusing on lift coefficient, stall characteristics, and maximum lift-to-drag ratio. The investigation includes the NACA23012C profile and configurations with different step geometries, ranging from one-step to five-step designs. Experimental measurements were conducted using a well-equipped aerodynamic laboratory, Institute of Aviation Engineering and Technology (IAET), Giza, Egypt. The lab features a wind tunnel, propeller test rig, and data acquisition system. The experiments were conducted meticulously to ensure accuracy and reproducibility, with a standardized method employed for uncertainty analysis. The results reveal distinct aerodynamic behaviors among the different configurations, highlighting the significant impact of design variations on aerodynamic performance. Notably, the three-step configuration consistently exhibited high performance, with a competitive or superior lift coefficient across a range of Reynolds numbers, showing an improvement of up to 35.1 %. Similarly, the four-step configuration demonstrated substantial increases in lift-to-drag ratios, reaching up to 53.2 %, while the five-step configuration exhibited varying trends with a minimum drag coefficient. The study also investigated stall characteristics and sensitivity to Reynolds numbers, revealing the complex trade-offs inherent in airfoil design. The findings provide valuable insights into optimizing airfoil performance under different operational conditions. Additionally, the adoption of two and three stepped airfoils resulted in significant reductions in blade material and associated costs for turbine blades.},
}

@article {pmid38991421,
year = {2024},
author = {Luciano, RD and da Silva, BL and Chen, XB and Bergstrom, DJ},
title = {Turbulent blood flow in a cerebral artery with an aneurysm.},
journal = {Journal of biomechanics},
volume = {172},
number = {},
pages = {112214},
doi = {10.1016/j.jbiomech.2024.112214},
pmid = {38991421},
issn = {1873-2380},
abstract = {Unruptured intracranial aneurysms are common in the general population, and many uncertainties remain when predicting rupture risks and treatment outcomes. One of the cutting-edge tools used to investigate this condition is computational fluid dynamics (CFD). However, CFD is not yet mature enough to guide the clinical management of this disease. In addition, recent studies have reported significant flow instabilities when refined numerical methods are used. Questions remain as to how to properly simulate and evaluate this flow, and whether these instabilities are really turbulence. The purpose of the present study is to evaluate the impact of the simulation setup on the results and investigate the occurrence of turbulence in a cerebral artery with an aneurysm. For this purpose, direct numerical simulations were performed with up to 200 cardiac cycles and with data sampling rates of up to 100,000 times per cardiac cycle. Through phase-averaging or triple decomposition, the contributions of turbulence and of laminar pulsatile waves to the velocity, pressure and wall shear stress fluctuations were distinguished. For example, the commonly used oscillatory shear index was found to be closely related to the laminar waves introduced at the inlet, rather than turbulence. The turbulence energy cascade was evaluated through energy spectrum estimates, revealing that, despite the low flow rates and Reynolds number, the flow is turbulent near the aneurysm. Phase-averaging was shown to be an approach that can help researchers better understand this flow, although the results are highly dependent on simulation setup and post-processing choices.},
}

@article {pmid38986513,
year = {2024},
author = {Maire, Y and Schmitt, FG and Kormas, K and Vasileiadis, S and Caruana, A and Skouroliakou, DI and Bampouris, V and Courcot, L and Hervé, F and Crouvoisier, M and Christaki, U},
title = {Effects of turbulence on diatoms of the genus pseudo-nitzschia spp. And associated bacteria.},
journal = {FEMS microbiology ecology},
volume = {},
number = {},
pages = {},
doi = {10.1093/femsec/fiae094},
pmid = {38986513},
issn = {1574-6941},
abstract = {Turbulence is one of the least investigated environmental factors impacting the ecophysiology of phytoplankton, both at the community and individual species level. Here, we investigated, for the first time, the effect of a turbulence gradient (${\rm{Reynolds\ number}}
$, from ${\rm{R}}
{{\rm{e}}
}_
{\rm{\lambda }}
= 0$ to ${\rm{R}}
{{\rm{e}}
}_
{\rm{\lambda }}
= 360$) on two species of the marine diatom Pseudo-nitzschia and their associated bacterial communities under laboratory conditions. Cell abundance, domoic acid (DA) production, chain formation, and Chl a content of P. fraudulenta and P. multiseries were higher for intermediate turbulence (${\rm{R}}
{{\rm{e}}
}_
{\rm{\lambda }}
= 160$ or $240$). DA was detectable only in P. multiseries samples. These observations were supported by transcriptomic analyses results which suggested the turbulence related induction of the expression of the DA production locus, with a linkage to an increased photosynthetic activity of the total metatranscriptome. This study also highlighted a higher richness of the bacterial community associated with the non-toxic strain of P. fraudulenta in comparison to the toxic strain of P. multiseries. Bacillus was an important genus in P. multiseries cultures (relative abundance 15.5%) and its highest abundances coincided with the highest DA levels. However, associated bacterial communities of both Pseudo-nitzschia species did not show clear patterns relative to turbulence intensity.},
}

@article {pmid38987632,
year = {2024},
author = {Oz, F and Kara, K},
title = {Controlling hypersonic boundary layer transition with localized cooling and metasurface treatments.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {15928},
pmid = {38987632},
issn = {2045-2322},
support = {OAC-1531128//National Science Foundation/ ; },
abstract = {This study investigates a novel method to control hypersonic boundary layer transition using a combined local cooling and local metasurface treatment. The method's effectiveness was investigated on a 5-degree half-angle blunt wedge with a nose radius of 0.0254 mm at a freestream Mach number of 6.0 using direct numerical simulations and linear stability theory. We explored four cases: (i) adiabatic baseline case, (ii) locally cooled case, (iii) local metasurface case, and (iv) combined local cooling-local metasurface case. Results showed that the combined local cooling-local metasurface treatment significantly reduced both wall pressure disturbance amplitude and the density perturbation amplitude around the sonic line, indicating a potential for controlling hypersonic boundary layer transition. In the local cooling-local metasurface case, the disturbance amplitude at the end of the computational domain was 270 times lower than the baseline case. The study also examined the impact of Reynolds numbers, ranging from 25.59 million per meter to 32.80 million per meter. Unsteady simulations revealed that the Reynolds number had a negligible effect on the local cooling-local metasurface performance, indicating that the proposed method applies to a wide range of flight conditions.},
}

@article {pmid38975123,
year = {2024},
author = {Nilpueng, K and Kaseethong, P and Wongwises, S},
title = {Heat transfer and flow characteristics of a plate-fin heat sink equipped with copper foam and twisted tapes.},
journal = {Heliyon},
volume = {10},
number = {12},
pages = {e32307},
doi = {10.1016/j.heliyon.2024.e32307},
pmid = {38975123},
issn = {2405-8440},
abstract = {The objective of this paper is to present new heat transfer enhancement approaches in plate-fin heat sinks (PFHS) using copper foam and twisted tapes. The motivation behind these concepts is to reduce pressure drop while enhancing heat transfer compared to PFHSs fully inserted with copper foam. The impact of twisted tape type, twist ratio, and Reynolds number (Re) on the heat and flow behaviors inside the PFHS equipped with copper foam (PFHSCF) is investigated. Copper foam has a porosity of 0.932 and a pore density of 40 pores per inch. Stationary and rotating twisted tapes with twist ratios between 2.7 and 4 are tested at Re between 3000 and 6000. The experimental results indicated that the pressure drop of the airflow inside a PFHS equipped with copper foam and a stationary twisted tape (PFHSCF_STT) as well as a PFHS equipped with copper foam and rotating twisted tapes (PFHSCF_RTT) decreased by an average of 34.8 % and 37.9 %, respectively, compared to a PFHSCF. When the twist ratio is decreased from 4 to 2.7, the thermal resistances of PFHSCF_STT and PFHSCF_RTT are reduced by 14.2 and 14.8 %, respectively. Based on assessment, the thermal-hydraulic performance of a PFHSCF_RTT with twist ratios of 2.7 and 3.3 is higher than that of a PFHSCF. To facilitate practical applications, correlations are proposed to predict the Nusselt number and friction factor. Additionally, considering the outcomes of the current study, conducting numerical investigations on the thermal performance of PFHS under different pore densities of copper foam and wider twist ratios of twisted tapes is recommended to determine optimal working conditions for future research.},
}

@article {pmid38971061,
year = {2024},
author = {Li, Z and Wang, B and Wang, F and Sun, B and Li, L},
title = {Flow dynamics and turbulent coherent structures around sediment reduction plates of a sewer system.},
journal = {Journal of environmental management},
volume = {366},
number = {},
pages = {121594},
doi = {10.1016/j.jenvman.2024.121594},
pmid = {38971061},
issn = {1095-8630},
abstract = {In the management of urban drainage networks, great interest has been generated in the removal of sediments from sewer systems. The unsteady three-dimensional (3D) flow and turbulent coherent structures surrounding sediment reduction plates in a sewer system are investigated by means of the detached-eddy simulation (DES). Particular emphasis is given to detailing the instantaneous velocity and vorticity fields within the grooves, along with an examination of the three-dimensional, long-term, average flow structure at a Reynolds number of approximately 10[5]. Velocity vectors demonstrate continuous flapping of the flow on the groove wall, periodically interacting with ejections of positive and negative vorticity originating from the grooves. The interaction between the three-dimensional groove flow and the shear flow leads to the downstream transport of patches of positive and negative vorticity, which significantly influence sediment transport. The high-velocity shear flows and strong vortices generated in undulating topography, as identified by the Q-criteria, are the key factors contributing to the efficient sediment reduction capabilities of the sediment reduction plates. The sediment reduction plates with partially enclosed structures exhibit low sedimentation rates in grooves on the plate, a broader acceleration region, and a lesser impact on the flow capacity. The results improve the understanding of the hydrodynamics and turbulent coherent structures surrounding the sediment reduction plates while elucidating the driving factors behind the enhancement of sediment scouring and suspension capacities. These results indicate that the redesign of the plates as partially enclosed structures contributes to further improving their sediment reduction performance.},
}

@article {pmid38968103,
year = {2024},
author = {Yang, W and Chen, MA and Lee, SH and Kang, PK},
title = {Fluid inertia controls mineral precipitation and clogging in pore to network-scale flows.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {28},
pages = {e2401318121},
doi = {10.1073/pnas.2401318121},
pmid = {38968103},
issn = {1091-6490},
support = {DE-SC0023429//U.S. Department of Energy (DOE)/ ; ECCS-2025124//National Science Foundation (NSF)/ ; },
abstract = {Mineral precipitation caused by fluid mixing presents complex control and predictability challenges in a variety of natural and engineering processes, including carbon mineralization, geothermal energy, and microfluidics. Precipitation dynamics, particularly under the influence of fluid flow, remain poorly understood. Combining microfluidic experiments and three-dimensional reactive transport simulations, we demonstrate that fluid inertia controls mineral precipitation and clogging at flow intersections, even in laminar flows. We observe distinct precipitation regimes as a function of Reynolds number (Re). At low Reynolds numbers (Re < 10), precipitates form a thin, dense layer along the mixing interface, which shuts precipitation off, while at high Reynolds numbers (Re > 50), strong three-dimensional flows significantly enhance precipitation over the entire intersection, resulting in rapid clogging. When injection rates from two inlets are uneven, flow symmetry-breaking leads to unexpected flow bifurcation phenomena, which result in enhanced concurrent precipitation in both downstream channels. Finally, we extend our findings to rough channel networks and demonstrate that the identified inertial effects on precipitation at the intersection scale are also present and even more dramatic at the network scale. This study sheds light on the fundamental mechanisms underlying mixing-induced mineral precipitation and provides a framework for designing and optimizing processes involving mineral precipitation.},
}

@article {pmid38958090,
year = {2024},
author = {Wang, H and Xiong, J and Cai, Y and Fu, W and Zhong, Y and Jiang, T and Cheang, UK},
title = {Stabilization of CsPbBr3 Nanowires Through SU-8 Encapsulation for the Fabrication of Bilayer Microswimmers with Magnetic and Fluorescence Properties.},
journal = {Small (Weinheim an der Bergstrasse, Germany)},
volume = {},
number = {},
pages = {e2400346},
doi = {10.1002/smll.202400346},
pmid = {38958090},
issn = {1613-6829},
support = {52375569//National Natural Science Foundation of China/ ; RCYX20210609103644015//Science and Technology Innovation Committee Foundation of Shenzhen/ ; 2021ZDZX2037//Department of Education of Guangdong/ ; 2021A1515110212//Guangdong Basic and Applied Basic Research Foundation/ ; 2023A1515012229//Guangdong Basic and Applied Basic Research Foundation/ ; },
abstract = {All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals have drawn great interest because of their excellent photophysical properties and potential applications. However, their poor stability in water greatly limited their use in applications that require stable structures. In this work, a facile approach to stabilize CsPbBr3 nanowires is developed by using SU-8 as a protection medium; thereby creating stable CsPbBr3/SU-8 microstructures. Through photolithography and layer-by-layer deposition, CsPbBr3/SU-8 is used to fabricate bilayer achiral microswimmers (BAMs), which consist of a top CsPbBr3/SU-8 layer and a bottom Fe3O4 magnetic layer. Compared to pure CsPbBr3 nanowires, the CsPbBr3/SU-8 shows long-term structural and fluorescence stability in water against ultrasonication treatment. Due to the magnetic layer, the motion of the microswimmers can be controlled precisely under a rotating magnetic field, allowing them to swim at low Reynolds number and tumble or roll on surfaces. Furthermore, CsPbBr3/SU-8 can be used to fabricate various types of planar microstructures with high throughput, high consistency, and fluorescence properties. This work provides a method for the stabilization of CsPbBr3 and demonstrates the potential to mass fabricate planar microstructures with various shapes, which can be used in different applications such as microrobotics.},
}

@article {pmid38950632,
year = {2024},
author = {Stachurska, B and Sulisz, W},
title = {Laboratory investigations of wave-induced transport of plastic debris over a rippled bottom.},
journal = {The Science of the total environment},
volume = {},
number = {},
pages = {174380},
doi = {10.1016/j.scitotenv.2024.174380},
pmid = {38950632},
issn = {1879-1026},
abstract = {Laboratory experiments are conducted in a wave flume to investigate the effect of water waves on the transport of plastic pellets over a rippled bottom. The horizontal velocities of plastic debris are analyzed over the rippled bottom for different wave conditions and plastic elements with different properties. Laboratory investigations determined the characteristic transport patterns of wave-induced plastic debris with a density of ~2.0g/cm3 moving along the rippled bottom. In the first, swing-type motion, the grains move only in the ripple trough with velocities lower than 0.10 m/s. For sliding-type movement, the grains move along the entire rippled surface with velocities in the range of 0.10-0.13 m/s. For higher velocities in the range of 0.15-0.20 m/s, a saltation-type motion becomes dominant. The results show that plastic grains may move up to 2-3 cm above the ripple crest depending on hydrodynamic conditions. The analysis shows that for velocity-skewed flows, sliding-type motion and onshore transport dominate. For acceleration-skewed flows, saltation-type motion and offshore transport dominate, which is attributed to higher boundary layer thickness and phase lag effects. The analysis of the relationship between the particle Reynolds number and the thickness of the turbulent boundary layer reveals that for values of Rep≥1000 and a boundary layer thickness mm saltation-type motion becomes dominant. The direction of transport is affected not only by the density of the sediment and the wave skewness coefficients but also by the dimensions of the bottom ripples. The laboratory investigations also provide insight into the hydrodynamic conditions affecting the transport of plastic debris along the bottom covered with ripples in oscillating nonlinear water flows.},
}

@article {pmid38947461,
year = {2024},
author = {Amsie, AB and Ayalew, AT and Mada, ZM and Finsa, MM},
title = {Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir.},
journal = {Heliyon},
volume = {10},
number = {11},
pages = {e32162},
pmid = {38947461},
issn = {2405-8440},
abstract = {The primary purpose of this study was to evaluate the hydraulic coefficient of coarse aggregate grain size beds and hydraulic parameters under random and perpendicular bed configurations, as well as to explore the discharge coefficient for rectangular weirs. The research objectives were to compare flow resistance coefficients, evaluate the discharge coefficient for rectangular weirs, investigate the relationship between roughness coefficient and hydraulic parameters, and validate the theoretical hydraulic equation for the rectangular weir. This was achieved by analysing different bed configurations, bed slopes, and 20 and 30-mm bed materials. Sieve analysis was conducted on bed materials using American-standard sieves to determine their particle size distribution. The experiment was performed in a rectangular flume measuring 12 m in length, 0.31 m in width, and 0.45 m in depth. In a laboratory experiment, water was pumped into a flume using centrifugal pumps, and a rectangular weir was attached downstream for discharge measurement. The experiment investigated factors such as Manning roughness coefficient, bed material geometry, bed slope, and weir shapes. Approximately 1680 tests were conducted to analysed the impact of these factors on discharge and the coefficient of discharge. The average Manning's roughness coefficients for a grain size of 20 mm were 0.019 (with weir) and 0.019 (without weir) in a random bed configuration, and 0.028 (with weir) and 0.027 (without weir) in a perpendicular flow bed configuration. For a grain size of 30 mm, the coefficients were 0.023 (with weir) and 0.022 (without weir) in a random bed configuration, and 0.033 (with weir) and 0.026 (without weir) in a perpendicular flow bed configuration. The presence of a weir has affected Manning's roughness coefficients and discharge coefficients. With a weir, the roughness coefficients have generally been higher compared to without a weir, indicating increased roughness in the channel. The discharge coefficient for a rectangular weir with a grain size of 20 mm ranged from 0.39 to 0.84 (random bed) and 0.27 to 0.68 (perpendicular flow bed), while for a grain size of 30 mm it ranged from 0.31 to 0.81 (random bed) and 0.23 to 0.48 (perpendicular flow bed). The discharge coefficients have varied depending on the grain size and bed configuration, reflecting different flow efficiencies over the weir. Rough particles influenced flow and Manning's roughness coefficient value, then reduced discharge and velocity values. Under two bed configurations and slopes, beds with a grain size of 30 mm have higher roughness coefficients compared to those with a grain size of 20 mm. The models have shown that the roughness coefficient is inversely proportional to the discharge and directly proportional to the tailgate water levels. The coefficient of roughness and discharge coefficient are mainly influenced by the channel slopes, bed roughness, bed grain size, and bed configuration. A randomly configured bed with a 20 mm grain size gravel bed is preferred over a perpendicular bed configuration to handle high discharges. Using a 20 mm grain-size gravel bed in open-channel flow is more suitable than a 30 mm grain-size bed. Relying on the constant friction factor, Manning's n, is not recommended as it may result in design errors. These findings have the potential to improve hydraulic engineering design practices, enhancing the accuracy and efficiency of open-channel flow systems.},
}

@article {pmid38947451,
year = {2024},
author = {Mahammedi, A and Tayeb, NT and Kim, JH and Hossain, S},
title = {Entropy generation analysis and thermal synergy efficiency in the T-shaped micro-kenics.},
journal = {Heliyon},
volume = {10},
number = {11},
pages = {e32233},
pmid = {38947451},
issn = {2405-8440},
abstract = {In this work, three different twist angles of a micro helical insert in a T-shaped are studied numerically in order to evaluate the laminar steady flow behavior of Newtonian fluid in chaotic geometry. In the geometries under consideration, thermal mixing behavior is carried out using fluids having two distinct input temperatures. Under the influence of chaotic advection and low rates of Reynolds number, the second law of thermodynamics is controlled in terms of the entropy generation caused by hydrodynamic and thermal processes. The governing equations are numerically solved using the CFD Fluent code. Thus, the micromixer's configuration demonstrated a very significant improvement in mixing degree while minimizing friction and thermal irreversibilities. The synergy coefficient, which depicts the link between velocity and heat transfer in angle form, is analyzed and the results are provided.},
}