Variation of Molecular Mean Free Path in Confined Geometries

JF Xie and L Gibelli and MK Borg and O Henrich and DA Lockerby and JM Reese, 31ST INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS (RGD31), 2132, 090009 (2019).

DOI: 10.1063/1.5119594

This paper aims to settle disputes in the literature about the spatial variation of the molecular mean free path (MFP) in confined geometries. The MFP of a gas is determined by using both molecular dynamics (MD) and the direct simulation Monte Carlo (DSMC) technique. In spatially- homogeneous cases, the numerical results exactly recover the kinetic theory predictions of a constant MFP. However, in microchannels, the MFP is found to vary near to the bounding walls and reduce at the surfaces to half of its bulk value as long as collisions between gas molecules and wall atoms are taken into account in the calculation of the MFP.

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