TY - JOUR

T1 - On the Anisotropy of Gas-Transfer Processes in Nanochannels and Microchannels

AU - Rudyak, V. Ya

AU - Lezhnev, E. V.

AU - Lubimov, D. N.

N1 - Funding Information: The work was partially supported by the Russian Foundation for Basic Research (grants no. 19-01-00399 and no. 20-01-00041) and the megagrant of the Ministry of Science and Higher Education of the Russian Federation (agreement no. 075-15-2021-575). Publisher Copyright: © 2022, Pleiades Publishing, Ltd.

PY - 2022/3

Y1 - 2022/3

N2 - The method of stochastic molecular modeling, developed by us for calculating the transport coefficients of rarefied gas in a bulk, is generalized to describe transport processes in confined conditions. The phase trajectories of the studied molecular system are simulated stochastically, and the simulation of the dynamics of a molecule is split into processes. First, its shift in configuration space is realized, and then a possible collision with other molecules is played out. The calculation of all observables, in particular, the transport coefficients is carried out by averaging over an ensemble of independent phase trajectories. The interaction of gas molecules with a boundary is described by specular or specular-diffuse laws. The efficiency of the algorithm is demonstrated by calculating the self-diffusion coefficient of argon in a nanochannel. The accuracy of modeling is investigated, its dependence on the number of particles and phase trajectories used for averaging. The viscosity of rarefied gases in the nanochannel is systematically studied. It is shown that it is nonisotropic, and its difference along and across the channel is determined by the interaction of gas molecules with the channel walls. By changing the material of the walls, it is possible to significantly change the viscosity of the gas, and it can be several times greater than in the volume, or less. The indicated anisotropy of viscosity is recorded not only in nanochannels, but also in microchannels.

AB - The method of stochastic molecular modeling, developed by us for calculating the transport coefficients of rarefied gas in a bulk, is generalized to describe transport processes in confined conditions. The phase trajectories of the studied molecular system are simulated stochastically, and the simulation of the dynamics of a molecule is split into processes. First, its shift in configuration space is realized, and then a possible collision with other molecules is played out. The calculation of all observables, in particular, the transport coefficients is carried out by averaging over an ensemble of independent phase trajectories. The interaction of gas molecules with a boundary is described by specular or specular-diffuse laws. The efficiency of the algorithm is demonstrated by calculating the self-diffusion coefficient of argon in a nanochannel. The accuracy of modeling is investigated, its dependence on the number of particles and phase trajectories used for averaging. The viscosity of rarefied gases in the nanochannel is systematically studied. It is shown that it is nonisotropic, and its difference along and across the channel is determined by the interaction of gas molecules with the channel walls. By changing the material of the walls, it is possible to significantly change the viscosity of the gas, and it can be several times greater than in the volume, or less. The indicated anisotropy of viscosity is recorded not only in nanochannels, but also in microchannels.

KW - diffusion

KW - molecular modeling

KW - nanochannel

KW - rarefied gas

KW - transfer processes

KW - viscosity

UR - http://www.scopus.com/inward/record.url?scp=85131357783&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/9dd3b5de-c549-3f7c-b59a-eeb63ed8e1a8/

U2 - 10.1134/S1063454122010125

DO - 10.1134/S1063454122010125

M3 - Article

AN - SCOPUS:85131357783

VL - 55

SP - 108

EP - 115

JO - Vestnik St. Petersburg University: Mathematics

JF - Vestnik St. Petersburg University: Mathematics

SN - 1063-4541

IS - 1

ER -