Novel Hybrid Hard Sphere Model for Direct Simulation Monte Carlo Computations

This paper concerns the development of a novel hybrid hard sphere molecular model in direct simulation Monte Carlo technique. Usually, the variable hard sphere model is applied to simulate molecular collisions. However, this model is not accurate enough when temperatures are quite low or extremely high. The generalized hard sphere model can give the viscosity behavior of gases more accurately over a wide temperature range, but it is seldom used in practical engineering applications due to its poor computational efficiency. In this paper, a hybrid hard sphere model is presented to improve the computational efficiency of the original generalized hard sphere model. The modification is based upon the variable hard sphere and generalized hard sphere models and agrees quite well with the experimental observations. To investigate the accuracy and capability of the newly proposed model, two test cases involving thermal equilibrium and nonequilibrium are simulated. The results are compared with those of existing models and experimental data. The results show that the computational efficiency of the new model is much higher than the original generalized hard sphere model especially at low temperatures.