Multi-Monte Carlo Methods for Inter-particle Collision

In the interest of improving collision arithmetic and decreasing computation cost, a new Multi-Monte Carlo (MMC) method for inter-particle collision is prompted. The particle motion is described by the Langevin equations, which is solved by Monte Carlo (MC) method. On the same time, Inter-particle collision is modeled by Direct Simulation Monte Carlo (DSMC) method. DSMC is coupled with forenamed MC method, as it is called Multi-Monte Carlo method. The simulation particle of MMC method is fictitious particle which number is far less than real particle. In order to form an integrated MMC method for inter-particle collision, a series of methods are developed, which include the restriction of the setting of time step, the guide line to judge in which control volume fictitious collision partner lies, the guide line to judge whether or not inter-particle collision event occurs, the choice rule of fictitious collision partner, and particle collision dynamics based on stochastic collision angle. Fine particles and heavy coarse particles flows are chosen as standard cases to validate MMC method. The simulation results of MMC methods are in good agreement with both theoretical solution and Direct Numerical Simulation (DNS), not only on macroscopical facets such as particle collision frequency but also on microcosmic facets such as the evolvement of particle fields. Numerical simulation proves MMC method for inter-particle collision not only has enough low computation cost but also gets to enough high computation precision.