The effect of characteristic length on mean free path for confined gases

S Hari and SK Prabha and SP Sathian, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, 437, 68-74 (2015).

DOI: 10.1016/j.physa.2015.05.022

Molecular Dynamics simulations are performed to investigate the influence of system boundaries and characteristic length (L) of the system on the mean free path (MFP) of rarefied gas confined to the walls of a nano-channel. Isothermal Lennard-Jones fluid confined between Reflective walls and platinum walls at different number densities (0.31 atoms/nm(3) and 1.61 atoms/nm(3)) are independently considered. The MFP is calculated by the Lagrangian approach of tracking the trajectory of each atom and averaging the distance between successive collisions. The percentage of fluid-wall collisions is observed to predominate over fluid-fluid collisions at high levels of rarefaction. The influence of L (varying from 6 nm to 16 nm) on MFP is examined in this regime. At lower Knudsen number (Kn), it is observed that the effect of L on MFP is minimal. However, at higher rarefaction the characteristic dimension influences the MFP significantly for various wall configurations. (C) 2015 Elsevier B.V. All rights reserved.

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