Heat and mass fluxes upon incomplete accommodation of rarefied gas molecules by the walls of an elliptic channel

Abstract

The free-molecular rarefied-gas flow in a long channel of elliptic cross-section is considered. The Maxwellian mirror-diffuse reflection model is used as the boundary condition on the channel walls. Under the assumption that a longitudinal temperature gradient is maintained in the channel the mass and heat fluxes are determined as functions of the accommodation coefficient and the ellipse semi-axis ratio. The gas mass velocity profile is obtained. It is shown that for the channels with the same ellipse semi-axis ratios a decrease in the accommodation coefficient leads generally to an increase in the gas mass velocity. The results obtained are compared with those for the case of full gas accommodation on the channel surface.