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Updated: Apr 16, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
Free-path distribution and Knudsen-layer modeling for gaseous flows in the transition regime
Quy Dong To1, Céline Léonard1, Guy Lauriat1
1Université Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée Cedex 2, France.
Abstract:
In this paper, we use molecular dynamics (MD) simulations to study the mean free path distribution of nonequilibrium gases in micronanochannel and to model the Knudsen (Kn) layer effect. It is found that the mean free path is significantly reduced near the wall and rather insensitive to flow types (Poiseuille or Couette). The Cercignani relation between the mean free path and the viscosity is adopted to capture the velocity behavior of the special zone in the framework of the extended Navier-Stokes (NS) equations. MD simulations of flows are carried out at different Kn numbers. Results are then compared with the theoretical model.
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