The Knudsen Paradox in Micro-Channel Poiseuille Flows with a Symmetric Particle

Kannan, Ananda Subramani; Narahari, Tejas Sharma Bangalore; Bharadhwaj, Yashas; Mark, Andreas; Sardina, Gaetano; Maggiolo, Dario; Sasic, Srdjan; Ström, Henrik

doi:10.3390/app11010351

Cited by 6 publications

(5 citation statements)

References 46 publications

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“…It is particularly suitable for modeling rarefied gas flows and can handle flow regimes where the continuum assumption breaks down. Kannan et al studied the effects of a stationary particle on a microchannel Poiseuille flow using the DSMC method, providing insights into the Knudsen paradox, whereby molecular models can be purely stochastic or purely deterministic [29].…”

Section: Molecularmentioning

confidence: 99%

Microfluidic Mixing: A Physics-Oriented Review

Saravanakumar,

Cicek

2023

Micromachines

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This comprehensive review paper focuses on the intricate physics of microfluidics and their application in micromixing techniques. Various methods for enhancing mixing in microchannels are explored, with a keen emphasis on the underlying fluid dynamics principles. Geometrical micromixers employ complex channel designs to induce fluid–fluid interface distortions, yielding efficient mixing while retaining manufacturing simplicity. These methods synergize effectively with external techniques, showcasing promising potential. Electrohydrodynamics harnesses electrokinetic phenomena like electroosmosis, electrophoresis, and electrothermal effects. These methods offer dynamic control over mixing parameters via applied voltage, frequency, and electrode positioning, although power consumption and heating can be drawbacks. Acoustofluidics leverages acoustic waves to drive microstreaming, offering localized yet far-reaching effects. Magnetohydrodynamics, though limited in applicability to certain fluids, showcases potential by utilizing magnetic fields to propel mixing. Selecting an approach hinges on trade-offs among complexity, efficiency, and compatibility with fluid properties. Understanding the physics of fluid behavior and rationalizing these techniques aids in tailoring the most suitable micromixing solution. In a rapidly advancing field, this paper provides a consolidated understanding of these techniques, facilitating the informed choice of approach for specific microfluidic mixing needs.

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Section: Molecularmentioning

confidence: 99%

Microfluidic Mixing: A Physics-Oriented Review

Saravanakumar,

Cicek

2023

Micromachines

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“…In MD simulations, Couette flow and Poiseuille flow are often used to study the flow of fluids at the molecular level [22][23][24][25][26][27]. In these simulations, the behavior of individual particles in response to external forces such as shear forces and pressure gradients is investigated.…”

Section: Introductionmentioning

confidence: 99%

Examination of Couette Flow with a Pressure Gradient and Heat Conduction Using Molecular Dynamics Simulation

Pala Öngül,

Kandemir

2024

Applied Sciences

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As computer capabilities improve, Molecular Dynamics simulations are becoming more important for solving various flow problems. In this study, Couette and Poiseuille flows at different wall temperatures were investigated using a hard-sphere Molecular Dynamics simulation approach. Although a low spacing ratio was used in the simulations, the results are valid for rarefied gas flows when proper scaling based on the Knudsen number was used because only binary collisions with a hard-sphere model were considered. The main focus of this study was the examination of the effects of various wall speeds, pressure gradients, and wall temperatures. A pressure gradient was generated by developing a modified selective periodicity condition in the flow direction. With the combined effect of the pressure gradient and the wall velocities, subsonic, transonic, and supersonic speeds in nanochannels were examined. With the combination of different parameters, 1260 simulation cases were conducted. The results showed that there are temperature and velocity slips that are dependent on not only the temperature and velocity values but also on the magnitudes of a pressure gradient. The pressure gradient also caused nonlinearities in temperature and velocity profiles.

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“…Despite the extensive interest in studying fluid flow at the micro-and nanoscales, numerical investigations of gas flow under nonequilibrium conditions are deficient in thermal analyses. Previous studies on thermal field analysis in microfluidics systems are mostly limited to the channels with uniform cross-sections (see, for instance, [37,[41][42][43][44][45][46][47][48]). Therefore, there is an indispensable need for detailed investigations on heat and fluid flow at the micro-and nanoscales under nonequilibrium conditions.…”

Section: Introductionmentioning

confidence: 99%

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

2021

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Gas flow and heat transfer in confined geometries at micro-and nanoscales differ considerably from those at macro-scales, mainly due to nonequilibrium effects such as velocity slip and temperature jump. Nonequilibrium effects increase with a decrease in the characteristic length-scale of the fluid flow or the gas density, leading to the failure of the standard Navier–Stokes–Fourier (NSF) equations in predicting thermal and fluid flow fields. The direct simulation Monte Carlo (DSMC) method is employed in the present work to investigate pressure-driven nitrogen flow in divergent microchannels with various divergence angles and isothermal walls. The thermal fields obtained from numerical simulations are analysed for different inlet-to-outlet pressure ratios (1.5≤Π≤2.5), tangential momentum accommodation coefficients, and Knudsen numbers (0.05≤Kn≤12.5), covering slip to free-molecular rarefaction regimes. The thermal field in the microchannel is predicted, heat-lines are visualised, and the physics of heat transfer in the microchannel is discussed. Due to the rarefaction effects, the direction of heat flow is largely opposite to that of the mass flow. However, the interplay between thermal and pressure gradients, which are affected by geometrical configurations of the microchannel and the applied boundary conditions, determines the net heat flow direction. Additionally, the occurrence of thermal separation and cold-to-hot heat transfer (also known as anti-Fourier heat transfer) in divergent microchannels is explained.

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The Knudsen Paradox in Micro-Channel Poiseuille Flows with a Symmetric Particle

Cited by 6 publications

References 46 publications

Microfluidic Mixing: A Physics-Oriented Review

Microfluidic Mixing: A Physics-Oriented Review

Examination of Couette Flow with a Pressure Gradient and Heat Conduction Using Molecular Dynamics Simulation

Pressure-Driven Nitrogen Flow in Divergent Microchannels with Isothermal Walls

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