Gas-surface interaction effects on rarefied gas flows around microbeams induced by temperature fields

Abstract

Without any initial pressure gradient, gas flows can be induced by temperature gradient and exert Knudsen (thermal) force on immersed structures. In order to investigate the influence of surface accommodation coefficients on rarefied gas flows around a cold-hot arm pair, the direct simulation Monte Carlo (DSMC) method is applied in combination with the Cercignani-Lampis-Lord (CLL) gas-surface interaction model. The research results highlight the sensitivity of flow fields, thermal fields, pressure and Knudsen force to the variations of normal energy accommodation coefficient (NEAC), and tangential momentum accommodation coefficient (TMAC). In particular, Knudsen force is a nonlinear function of NEAC and TMAC respectively. With the accommodation coefficients decreasing, the slope of the curve (absolute value) increases. Furthermore, Knudsen force has a decreasing-increasing (in the opposite direction) trend with the decrease of NEAC. In contrast, Knudsen force keeps increasing with the decrease of TMAC. For example, Knudsen force increases approximately by 1.98, 2.37, and 8.37 times with pressures of 155 Pa, 387 Pa, and 966 Pa respectively when TMAC decreases from 1.0 to 0.1.