Novel Efficient Particle-Based Hybrid Approach for Modeling Hypersonic Rarefied Flows

Abstract

In the present work, a new two-dimensional parallel particle-based hybrid flow solver has been developed that couples the direct simulation Monte Carlo method and dynamic collision limiter method to simulate multiscale hypersonic rarefied flows. The Kolmogorov–Smirnov statistical test is used as the continuum breakdown parameter in this work. Based on the continuum breakdown parameter, the direct simulation Monte Carlo method is used where nonequilibrium flow regions are encountered, and the dynamic collision limiter method is used where flow regions are found to be in near-equilibrium state. The dynamic collision limiter scheme dynamically assigns a different number of collisions in cells per time step based on the local value of the Kolmogorov–Smirnov parameter such that the number of collisions is limited in near-equilibrium flow regions. Hypersonic flows over a wedge and Soyuz reentry capsule are simulated in the present work at widely different Knudsen numbers, and results are compared with other numerical data and with those obtained from the regular direct simulation Monte Carlo method. The hybrid direct simulation Monte Carlo/dynamic collision limiter particle scheme is shown to be as accurate as direct simulation Monte Carlo for the two flow problems considered in this work, with savings in the computational cost as compared with the direct simulation Monte Carlo method. Thus, the range of applicability of the direct simulation Monte Carlo method can be increased to handle higher density flows by using the direct simulation Monte Carlo/dynamic collision limiter numerical approach developed in this work.