Numerical Analysis of Gas-Surface Interaction by Molecular Dynamics Method. 3rd Report. Analysis on transferred energy and velocity distribution after collision.

Abstract

Much uncertainty exists in the numerical simulation of rarefied gas flow because of the unreliable models of boundary condition on a solid surface. In order to construct a new model, we must obtain much information on the micro-scale dynamics of gas-surface interaction. The behavior of a Xe gas molecule which collides with the clean Pt(111) surface of a very thin film is computed using the classical molecular dynamics method. The energy transferred from gas molecule to surface molecules is analyzed. The energy distribution is almost normal, and varies with the position of collision in the surface lattice. The average of the transferred energy agrees quantitatively with the results of soft cube model. The wall temperature exerts an effect on the deviation of the transferred energy, and not on its average. We developed a very simple scattering model with 'multi-stage' which can reproduce the very distorted distribution of velocity of gas molecule immediately after the first collision.