Conservative species weighting scheme for the direct simulation Monte Carlo method

The direct simulation Monte Carlo method (DSMC) finds application to nonequilibrium gas flows including hypersonic aerodynamics, spacecraft propulsion, materials synthesis, and flows in micromachines, In many of these problems, the species of most interest are present in very small quantities. This presents a resolution problem for the DSMC technique in which a finite number of particles is employed. This study proposes a new numerical scheme for the simulation of trace species. Unlike an existing scheme, the new method explicitly conserves both linear momentum and energy during collisions. The scheme is applied to a number of problems to demonstrate its accuracy and utility, Reduced execution times and improved resolution of trace species properties may be obtained simultaneously with the new method.