Effect of collision-partner selection schemes on the accuracy and efficiency of the direct simulation Monte Carlo method

The effect of the collision-partner selection scheme on the accuracy and the efficiency of the Direct Simulation Monte Carlo method is investigated. Several schemes that reduce the mean collision separation, including the fixed sub-cell scheme, the transient adaptive sub-cell scheme, and the virtual sub-cell scheme, are evaluated. Additionally, a new scheme is proposed that limits the population from which collision partners are selected based on the distance traveled by a simulator and performs near-neighbor collisions using this population. These collision-partner selection schemes are assessed for Fourier flow (heat conduction between parallel plates) and a standard hypersonic benchmark problem (Mach 15.6 nitrogen flow over a 25-55 degrees biconic). The new limited-selection near-neighbor scheme has superior performance compared to the other schemes for both flows and reduces both the spatial and temporal discretization errors relative to random-selection and nearest-neighbor collision-partner selection schemes. Copyright (C) 2010 John Wiley & Sons, Ltd.