Particle behavior simulation considering thermophoretic and drag forces by direct simulation Monte Carlo method

Abstract

A micro size particle behavior considering thermophoretic and drag forces are simulated by using direct simulation Monte Carlo (DSMC) method. The computation time is too high to compute the micro particle movement by conventional DSMC method because the computation time is proportional to a particle diameter. In this paper, the molecule-particle collision model, which computes the collision between a particle and multi molecules in a collision event, is considered. The momentum transfer to the particle is computed with a collision weight factor, where the collision weight factor means the number of molecules colliding with a particle in a collision event. The large time step is adopted by considering the collision weight factor. Therefore, the computation time becomes fifty thousandth times for micro size particle computation theoretically. We simulate the particle motion considering thermophoretic and drag forces by DSMC-Neutrals (Particle-PLUS neutral module) with above molecule-particle collision model, where DSMC-Neutrals is commercial software adopting DSMC method. The thermophoretic velocity with molecule-particle collision model is verified by comparison with Waldmann's model. Furthermore, it is shown that the DSMC method with molecule-particle collision model reproduces completely the conventional DSMC method. The behavior of a particle, which is polystyrene latex (PSL), is simulated.