Thermal transpiration flows induced by differences in accommodation coefficients

Abstract

The behavior of a rarefied gas between two parallel plates, each having its uniform temperature but having a square wave-like distribution of the accommodation coefficients, is numerically analyzed using the Direct Simulation Monte Carlo method. The gas temperature near the plate becomes close to the plate temperature only if the accommodation coefficient of the wall is large enough. A lower accommodation coefficient leads to the difference between the gas temperature and the adjacent wall. This temperature distribution induces a gas flow similar to the well-known thermal transpiration flow along the plate. When only one plate has a wave-like distribution of the accommodation coefficients, an array of vortical flow is induced between the plates. The magnitude of the vortex is linear to the difference in the accommodation coefficients. When both plates have a wave-like distribution of the accommodation coefficients, a one-way flow through the channel between the plates is induced. This flow depends on the phase difference of the discontinuity point. The size of one-way flow is nonlinear to the difference in accommodation coefficients.