1
|
Rahmani H, Larachi F, Taghavi SM. Modeling of Shear Flows over Superhydrophobic Surfaces: From Newtonian to Non-Newtonian Fluids. ACS ENGINEERING AU 2024; 4:166-192. [PMID: 38646519 PMCID: PMC11027103 DOI: 10.1021/acsengineeringau.3c00048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/07/2023] [Accepted: 12/11/2023] [Indexed: 04/23/2024]
Abstract
The design and use of superhydrophobic surfaces have gained special attentions due to their superior performances and advantages in many flow systems, e.g., in achieving specific goals including drag reduction and flow/droplet handling and manipulation. In this work, we conduct a brief review of shear flows over superhydrophobic surfaces, covering the classic and recent studies/trends for both Newtonian and non-Newtonian fluids. The aim is to mainly review the relevant mathematical and numerical modeling approaches developed during the past 20 years. Considering the wide ranges of applications of superhydrophobic surfaces in Newtonian fluid flows, we attempt to show how the developed studies for the Newtonian shear flows over superhydrophobic surfaces have been evolved, through highlighting the major breakthroughs. Despite the fact that, in many practical applications, flows over superhydrophobic surfaces may show complex non-Newtonian rheology, interactions between the non-Newtonian rheology and superhydrophobicity have not yet been well understood. Therefore, in this Review, we also highlight emerging recent studies addressing the shear flows of shear-thinning and yield stress fluids in superhydrophobic channels. We focus on reviewing the models developed to handle the intricate interaction between the formed liquid/air interface on superhydrophobic surfaces and the overlying flow. Such an intricate interaction will be more complex when the overlying flow shows nonlinear non-Newtonian rheology. We conclude that, although our understanding on the Newtonian shear flows over superhydrophobic surfaces has been well expanded via analyzing various aspects of such flows, the non-Newtonian counterpart is in its early stages. This could be associated with either the early applications mainly concerning Newtonian fluids or new complexities added to an already complex problem by the nonlinear non-Newtonian rheology. Finally, we discuss the possible directions for development of models that can address complex non-Newtonian shear flows over superhydrophobic surfaces.
Collapse
Affiliation(s)
- Hossein Rahmani
- Department of Chemical Engineering, Université Laval, Québec, QC, Canada G1 V 0A6
| | - Faïçal Larachi
- Department of Chemical Engineering, Université Laval, Québec, QC, Canada G1 V 0A6
| | | |
Collapse
|
2
|
Liu C, Legchenkova I, Han L, Ge W, Lv C, Feng S, Bormashenko E, Liu Y. Directional Droplet Transport Mediated by Circular Groove Arrays. Part I: Experimental Findings. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9608-9615. [PMID: 32787135 DOI: 10.1021/acs.langmuir.0c01733] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Directional transport of liquid droplets is crucial for various applications including water harvesting, anti-icing, and condensation heat transfer. Here, bouncing of water droplets with patterned superhydrophobic surfaces composed of circular equidistant grooves was studied. The directional transport of droplets toward the pole of the grooves was observed. The impact of the Weber number, initial polar distance r, and geometrical parameters of the surface on the directional droplet bouncing was experimentally explored. The nature of bouncing was switched when the Weber numbers exceeded We ≅ 20-25. The rebouncing height was slightly dependent on the initial polar coordinate of the impact point for a fixed We, whereas it grew for We > 20. The weak dependence of the droplet spreading time on the Weber number was close to the dependence predicted by the Hertz bouncing, thus evidencing the negligible influence of viscosity in the process. Change in the scaling exponent describing the dependence of the normalized spreading time on the Weber number was registered for We ≅ 25. The universal dependence of the offset distance ΔL of the droplets on the Weber number ΔL/D0 ∼ We1.5 was established. The normalized offset distance decreased with the normalized initial polar distance as ΔL/D0 ∼ (r/S)-1, where D0 and S are the droplet diameter and groove width, respectively. This research may yield more insights into droplet bouncing on patterned surfaces and offer more options in directed droplet transportation.
Collapse
Affiliation(s)
- Cong Liu
- Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Irina Legchenkova
- Chemical Engineering Department, Engineering Faculty, Ariel University, Ariel 40700, Israel
| | - Libao Han
- Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Wenna Ge
- Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Cunjing Lv
- Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - Shile Feng
- Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Edward Bormashenko
- Chemical Engineering Department, Engineering Faculty, Ariel University, Ariel 40700, Israel
| | - Yahua Liu
- Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| |
Collapse
|
3
|
Vagner SA, Patlazhan SA. Flow Structure and Mixing Efficiency of Viscous Fluids in Microchannel with a Striped Superhydrophobic Wall. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16388-16399. [PMID: 31692363 DOI: 10.1021/acs.langmuir.9b02884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The peculiarities of a Newtonian fluid flow structure in microchannels with a striped superhydrophobic lower wall texture are studied by means of numerical modeling. In the Cassie-Baxter state, an oblique orientation of such a texture induces helicoidal streamlines with micro spirals. Such a flow structure favors the enhancement of fluid mixing efficiency, which can be quantified using the total root-mean-square deviation of streamlines from the microchannel axis. This characteristic was shown to be a nonmonotonic function of the striped texture tilt angle and to depend strongly on microchannel thickness. The mechanisms of micro and macro helicoidal flow structure formation are investigated, and the mixing quality of miscible fluids is estimated for various Peclet numbers and texture tilt angles. It was found that the striped superhydrophobic wall leads to a notable enhancement in the microchannel mixing efficiency at sufficiently large Peclet numbers.
Collapse
Affiliation(s)
- Sergey A Vagner
- Institute of Problems of Chemical Physics , Russian Academy of Sciences , 1, Academician Semenov Avenue , Chernogolovka , Moscow , 142432 , Russia
| | - Stanislav A Patlazhan
- Institute of Problems of Chemical Physics , Russian Academy of Sciences , 1, Academician Semenov Avenue , Chernogolovka , Moscow , 142432 , Russia
- Semenov Federal Research Center for Chemical Physics , Russian Academy of Sciences , 4, Kosygin Street , Moscow , 119991 , Russia
| |
Collapse
|
4
|
Patlazhan S, Vagner S. Apparent slip of shear thinning fluid in a microchannel with a superhydrophobic wall. Phys Rev E 2018; 96:013104. [PMID: 29347200 DOI: 10.1103/physreve.96.013104] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Indexed: 11/07/2022]
Abstract
The peculiarities of simple shear flow of shear thinning fluids over a superhydrophobic wall consisting of a set of parallel gas-filled grooves and solid stripes (domains with slip and stick boundary conditions) are studied numerically. The Carreau-Yasuda model is used to provide further insight into the problem of the slip behavior of non-Newtonian fluids having a decreasing viscosity with a shear rate increase. This feature is demonstrated to cause a nonlinear velocity profile leading to the apparent slip. The corresponding transverse and longitudinal apparent slip lengths of a striped texture are found to be noticeably larger than the respective effective slip lengths of Newtonian liquids in microchannels of various thicknesses and surface fractions of the slip domains. The viscosity distribution of the shear thinning fluid over the superhydrophobic wall is carefully investigated to describe the mechanism of the apparent slip. Nonmonotonic behavior of the apparent slip length as a function of the applied shear rate is revealed. This important property of shear thinning fluids is considered to be sensitive to the steepness of the viscosity flow curve, thus providing a way to decrease considerably the flow resistance in microchannels.
Collapse
Affiliation(s)
- Stanislav Patlazhan
- Semenov Institute of Chemical Physics of the Russian Academy of Sciences, 4 Kosygin Street, Moscow 119991, Russia.,Institute of Problems of Chemical Physics of the Russian Academy of Sciences, 1 Semenov Avenue, Chernogolovka, Moscow Region 142432, Russia
| | - Sergei Vagner
- Institute of Problems of Chemical Physics of the Russian Academy of Sciences, 1 Semenov Avenue, Chernogolovka, Moscow Region 142432, Russia
| |
Collapse
|
5
|
Kabedev A, Ross-Lonergan M, Lobaskin V. Hydrodynamic lift forces on solutes in a tilted nanopillar array: A computer simulation study. Electrophoresis 2017; 38:2479-2487. [PMID: 28755416 DOI: 10.1002/elps.201700130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 07/04/2017] [Accepted: 07/17/2017] [Indexed: 11/10/2022]
Abstract
We study solute transport in a microfluidic channel, where the walls hold an array of tilted rigid nanopillars. By solving numerically the flow equations in the channel, we show that a combination of hydrodynamic effects with excluded volume interactions between the solute particles and the pillars leads to a hydrodynamic lift effect, which varies with the particle size, and depends in a strongly nonlinear fashion on the flow rate. We show that the lift force can be sufficiently strong to drive the solute accumulation or removal from the pillar region and can be switched to the opposite direction by variation of the shear rate or driving pressure. We also demonstrate that the nanopillar array can be used to selectively attract particles of certain size and enhance solute trapping at the surface.
Collapse
Affiliation(s)
- Aleksei Kabedev
- School of Physics, University College Dublin, Dublin 4, Ireland
| | - Mark Ross-Lonergan
- Nevis Laboratories, Department of Physics, Columbia University, Irvington, NY, USA
| | | |
Collapse
|
6
|
Szuttor K, Roy T, Hardt S, Holm C, Smiatek J. The stretching force on a tethered polymer in pressure-driven flow. J Chem Phys 2017; 147:034902. [DOI: 10.1063/1.4993619] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kai Szuttor
- Institute for Computational Physics, University of Stuttgart, Allmandring 3, D-70569 Stuttgart, Germany
| | - Tamal Roy
- Institute for Nano- and Microfluidics, Technische Universität Darmstadt, Alarich-Weiss-Strasse 10, D-64287 Darmstadt, Germany
| | - Steffen Hardt
- Institute for Nano- and Microfluidics, Technische Universität Darmstadt, Alarich-Weiss-Strasse 10, D-64287 Darmstadt, Germany
| | - Christian Holm
- Institute for Computational Physics, University of Stuttgart, Allmandring 3, D-70569 Stuttgart, Germany
| | - Jens Smiatek
- Institute for Computational Physics, University of Stuttgart, Allmandring 3, D-70569 Stuttgart, Germany
| |
Collapse
|
7
|
Nizkaya TV, Dubov AL, Mourran A, Vinogradova OI. Probing effective slippage on superhydrophobic stripes by atomic force microscopy. SOFT MATTER 2016; 12:6910-6917. [PMID: 27476481 DOI: 10.1039/c6sm01074a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
While the effective slippage of water past superhydrophobic surfaces has been studied over a decade, theoretical predictions have never been properly confirmed by experiments. Here we measure a drag force on a sphere approaching a plane decorated by superhydrophobic grooves and compare the results with the predictions of semi-analytical theory developed here, which employs the gas cushion model to calculate the local slip length at the gas sectors. We demonstrate that at intermediate and large (compared to a texture period) separations the half-sum of longitudinal and transverse effective slip lengths can be deduced from the force-distance curve by using the known analytical theory of hydrodynamic interaction of a sphere with a homogeneous slipping plane. This half-sum is shown to depend on the fraction of gas sectors and its value is in excellent agreement with theoretical predictions. At small distances the half-sum of effective longitudinal and transverse slip lengths becomes separation-dependent, and is in quantitative agreement with the predictions of our semi-analytical theory.
Collapse
Affiliation(s)
- Tatiana V Nizkaya
- A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Alexander L Dubov
- A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia. and DWI - Leibniz Institute for Interactive Materials, RWTH Aachen, Forckenbeckstr. 50, 52056 Aachen, Germany
| | - Ahmed Mourran
- DWI - Leibniz Institute for Interactive Materials, RWTH Aachen, Forckenbeckstr. 50, 52056 Aachen, Germany
| | - Olga I Vinogradova
- A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia. and DWI - Leibniz Institute for Interactive Materials, RWTH Aachen, Forckenbeckstr. 50, 52056 Aachen, Germany and Department of Physics, M.V.Lomonosov Moscow State University, 119991 Moscow, Russia
| |
Collapse
|
8
|
Asmolov ES, Dubov AL, Nizkaya TV, Kuehne AJC, Vinogradova OI. Principles of transverse flow fractionation of microparticles in superhydrophobic channels. LAB ON A CHIP 2015; 15:2835-2841. [PMID: 26016651 DOI: 10.1039/c5lc00310e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We propose a concept of fractionation of micron-sized particles in a microfluidic device with a bottom wall decorated by superhydrophobic stripes. The stripes are oriented at an angle α to the direction of a driving force, G, which generally includes an applied pressure gradient and gravity. Separation relies on the initial sedimentation of particles under gravity in the main forward flow, and their subsequent lateral deflection near a superhydrophobic wall due to generation of a secondary flow transverse to G. We provide some theoretical arguments allowing us to quantify the transverse displacement of particles in the microfluidic channel, and confirm the validity of theoretical predictions in test experiments with monodisperse fractions of microparticles. Our results can guide the design of superhydrophobic microfluidic devices for efficient sorting of microparticles with a relatively small difference in size and density.
Collapse
Affiliation(s)
- Evgeny S Asmolov
- A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | | | | | | | | |
Collapse
|
9
|
Maduar SR, Belyaev AV, Lobaskin V, Vinogradova OI. Electrohydrodynamics near hydrophobic surfaces. PHYSICAL REVIEW LETTERS 2015; 114:118301. [PMID: 25839314 DOI: 10.1103/physrevlett.114.118301] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Indexed: 06/04/2023]
Abstract
We show that an electro-osmotic flow near the slippery hydrophobic surface depends strongly on the mobility of surface charges, which are balanced by counterions of the electrostatic diffuse layer. For a hydrophobic surface with immobile charges, the fluid transport is considerably amplified by the existence of a hydrodynamic slippage. In contrast, near the hydrophobic surface with mobile adsorbed charges, it is also controlled by an additional electric force, which increases the shear stress at the slipping interface. To account for this, we formulate electrohydrodynamic boundary conditions at the slipping interface, which should be applied to quantify electro-osmotic flows instead of hydrodynamic boundary conditions. Our theoretical predictions are fully supported by dissipative particle dynamics simulations with explicit charges. These results lead to a new interpretation of zeta potential of hydrophobic surfaces.
Collapse
Affiliation(s)
- S R Maduar
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia
- Department of Physics, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia
| | - A V Belyaev
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia
- Department of Physics, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia
- Federal Research and Clinical Center of Pediatric Hematology, Oncology and Immunology, 1 Samora Machel street, 117997 Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology RAS, 38A Leninsky Prospect, 119991 Moscow, Russia
| | - V Lobaskin
- School of Physics and CASL, University College Dublin, Belfield, Dublin 4, Ireland
| | - O I Vinogradova
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia
- Department of Physics, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia
- DWI-Leibniz Institute for Interactive Materials, RWTH Aachen, Forckenbeckstraße 50, 52056 Aachen, Germany
| |
Collapse
|
10
|
Nizkaya TV, Asmolov ES, Zhou J, Schmid F, Vinogradova OI. Flows and mixing in channels with misaligned superhydrophobic walls. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:033020. [PMID: 25871215 DOI: 10.1103/physreve.91.033020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Indexed: 06/04/2023]
Abstract
Aligned superhydrophobic surfaces with the same texture orientation reduce drag in the channel and generate secondary flows transverse to the direction of the applied pressure gradient. Here we show that a transverse shear can be easily generated by using superhydrophobic channels with misaligned textured surfaces. We propose a general theoretical approach to quantify this transverse flow by introducing the concept of an effective shear tensor. To illustrate its use, we present approximate theoretical solutions and Dissipative Particle Dynamics simulations for striped superhydrophobic channels. Our results demonstrate that the transverse shear leads to complex flow patterns, which provide a new mechanism of a passive vertical mixing at the scale of a texture period. Depending on the value of Reynolds number two different scenarios occur. At relatively low Reynolds number the flow represents a transverse shear superimposed with two corotating vortices. For larger Reynolds number these vortices become isolated, by suppressing fluid transport in the transverse direction.
Collapse
Affiliation(s)
- Tatiana V Nizkaya
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Science, 31 Leninsky Prospect, 119991 Moscow, Russia
| | - Evgeny S Asmolov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Science, 31 Leninsky Prospect, 119991 Moscow, Russia
- Central Aero-Hydrodynamic Institute, 140180 Zhukovsky, Moscow region, Russia
| | - Jiajia Zhou
- Institut für Physik, Johannes Gutenberg-Universität Mainz, D55099 Mainz, Germany
| | - Friederike Schmid
- Institut für Physik, Johannes Gutenberg-Universität Mainz, D55099 Mainz, Germany
| | - Olga I Vinogradova
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Science, 31 Leninsky Prospect, 119991 Moscow, Russia
- Department of Physics, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia
- DWI-Leibniz Institute for Interactive Materials, RWTH Aachen, Forckenbeckstrasse 50, 52056 Aachen, Germany
| |
Collapse
|
11
|
Medina S, Zhou J, Wang ZG, Schmid F. An efficient dissipative particle dynamics-based algorithm for simulating electrolyte solutions. J Chem Phys 2015; 142:024103. [DOI: 10.1063/1.4905102] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
12
|
Dubov AL, Schmieschek S, Asmolov ES, Harting J, Vinogradova OI. Lattice-Boltzmann simulations of the drag force on a sphere approaching a superhydrophobic striped plane. J Chem Phys 2014; 140:034707. [DOI: 10.1063/1.4861896] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
13
|
Zhou J, Asmolov ES, Schmid F, Vinogradova OI. Effective slippage on superhydrophobic trapezoidal grooves. J Chem Phys 2013; 139:174708. [DOI: 10.1063/1.4827867] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
14
|
Asmolov ES, Zhou J, Schmid F, Vinogradova OI. Effective slip-length tensor for a flow over weakly slipping stripes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:023004. [PMID: 24032921 DOI: 10.1103/physreve.88.023004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/19/2013] [Indexed: 06/02/2023]
Abstract
We discuss the flow past a flat heterogeneous solid surface decorated by slipping stripes. The spatially varying slip length, b(y), is assumed to be small compared to the scale of the heterogeneities, L, but finite. For such weakly slipping surfaces, earlier analyses have predicted that the effective slip length is simply given by the surface-averaged slip length, which implies that the effective slip-length tensor becomes isotropic. Here we show that a different scenario is expected if the local slip length has steplike jumps at the edges of slipping heterogeneities. In this case, the next-to-leading term in an expansion of the effective slip-length tensor in powers of max[b(y)/L] becomes comparable to the leading-order term, but anisotropic, even at very small b(y)/L. This leads to an anisotropy of the effective slip and to its significant reduction compared to the surface-averaged value. The asymptotic formulas are tested by numerical solutions and are in agreement with results of dissipative particle dynamics simulations.
Collapse
Affiliation(s)
- Evgeny S Asmolov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia and Central Aero-Hydrodynamic Institute, 140180 Zhukovsky, Moscow region, Russia and Institute of Mechanics, M. V. Lomonosov Moscow State University, 119071 Moscow, Russia
| | | | | | | |
Collapse
|
15
|
Pham TT, To QD, Lauriat G, Léonard C. Tensorial slip theory for gas flows and comparison with molecular dynamics simulations using an anisotropic gas-wall collision mechanism. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:053012. [PMID: 23767625 DOI: 10.1103/physreve.87.053012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Indexed: 06/02/2023]
Abstract
In this paper we examine the anisotropic slip theory for gas flows based on tangential accommodation coefficients and compare it with molecular dynamics (MD) results. A special gas-wall boundary condition is employed within MD simulations to mimic the anisotropic gas-wall collision mechanism. Results from MD simulations with different surface orientations show good agreement with the slip quantification proposed in this work.
Collapse
Affiliation(s)
- Thanh Tung Pham
- Laboratoire Modelisation et Simulation Multi Echelle UMR 8208 CNRS, Universite Paris-Est, 5 Boulevard Descartes, 77454 Marne-la-Vallee, Cedex 2, France
| | | | | | | |
Collapse
|
16
|
Asmolov ES, Schmieschek S, Harting J, Vinogradova OI. Flow past superhydrophobic surfaces with cosine variation in local slip length. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:023005. [PMID: 23496608 DOI: 10.1103/physreve.87.023005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Indexed: 06/01/2023]
Abstract
Anisotropic superhydrophobic surfaces have the potential to greatly reduce drag and enhance mixing phenomena in microfluidic devices. Recent work has focused mostly on cases of superhydrophobic stripes. Here, we analyze a relevant situation of cosine variation of the local slip length. We derive approximate formulas for maximal (longitudinal) and minimal (transverse) directional effective slip lengths that are in good agreement with the exact numerical solution and lattice-Boltzmann simulations. Compared to the case of superhydrophobic stripes, the cosine texture can provide a very large effective slip. However, the difference between eigenvalues of the slip-length tensor is smaller, indicating that the flow is less anisotropic.
Collapse
Affiliation(s)
- Evgeny S Asmolov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia
| | | | | | | |
Collapse
|
17
|
Vinogradova OI, Dubov AL. Superhydrophobic Textures for Microfluidics. MENDELEEV COMMUNICATIONS 2012. [DOI: 10.1016/j.mencom.2012.09.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|