Gas-surface scattering effect on vacuum gas flows through rectangular channels

Abstract

Flow of a rarefied gas through a channel of rectangular cross section is investigated numerically and experimentally. Emphasis is given on the study of the molecular scattering law influence at the wall boundary surfaces. The Cercignani-Lampis boundary conditions are considered in detail for the current problem, along with the linearized BGK kinetic model and the discrete velocity method. Numerical conductance values are tabulated for certain aspect ratios and accommodation coefficients in the whole range of the Knudsen number and compared with corresponding experimental results for certain gas-surface combinations. Compared to the classical Maxwell diffuse boundary conditions, the Cercignani-Lampis gas-surface interaction allows a better agreement with the measurements. (C) 2011 Elsevier Ltd. All rights reserved