Computation of Hypersonic Flows Using the Direct Simulation Monte Carlo Method

The direct simulation MonteCarlo method has evolved over 50years into a powerful numerical technique for the computation of complex, nonequilibrium gas flows. In this context, "nonequilibrium" means that the velocity distribution function is not in an equilibrium form due to a low number of intermolecular collisions within a fluid element. In hypersonic flow, nonequilibrium conditions occur at high altitude and in regions of flowfields with small length scales. In this paper, the theoretical basis of the direct simulation MonteCarlo technique is discussed. In addition, the methods used in direct simulation MonteCarlo are described for simulation of high-temperature, real gas effects and gas-surface interactions. Several examples of the application of direct simulation MonteCarlo to flows around blunt hypersonic vehicles are presented to illustrate current capabilities. Areas are highlighted where further research on the direct simulation MonteCarlo technique is required.