Statistical error analysis for the direct simulation Monte Carlo technique

The statistical error associated with the direct simulation Monte Carte technique is studied when it is applied to nonequilibrium hypersonic and nozzle flows. A root mean square (rms) error is employed as an indicator of the level of the statistical fluctuations. The effects of number of particles per cell and sample size are analyzed and quantified. It is found that in order to adequately model the physics of interest, the number of particles in the simulation must be greater than a certain minimum. An equation is developed to model and analyze the rms errors. A range is provided of the appropriate number of particles to be employed in the simulation in order to achieve the smallest statistical error at a fixed computational cost. Values are also recommended for the maximum number of sampling time steps to be used for efficient computation on memory limited computers. The effects of collision model acid of cloning particles on the statistical scatter are analyzed. (C) 1996 Academic Press, Inc.