Reseach On Microscopic And Transient Numerical Method For Hypersonic Flows

Based on the analysis of hypersonic flows and the characteristics of existing hypersonic research methods, this paper proposes Direct Simulation Monte Carlo (DSMC) method as a common numerical method in hypersonic flows, and studies a lot. In this paper, the basic idea of DSMC method and numerical models is briefly introduced. In addition, this paper validate that the method is an effective means of hypersonic through theory.Taking into account the huge amount of computational cost on simulating high-density and large scope flows with DSMC method, this paper proposes the use of high-performance computing as upgrading application of the DSMC method. Then four parallel strategies are analyzed, and a suitable strategy for the present stage is chosen. The numerical experiment certificate that the chosen parallel strategy in the calculation has a lot of improvement in efficiency actually. Other existing disadvantage for DSMC method is hard to handle complex shape. This paper proposes the use of non-structural mesh combining with particle tracking methods, and applied in program. We use the structure mesh generation method at this stage, but deal with non-structural mesh in solution. Grid method will be researched to make DSMC as a genetic method.This paper also analyzes the validity of the numerical methods. Comparing the simulation-particle-weight parameters, time-step, and steady-discrimination, this paper proposed some effective criterions.In addition, this paper proposes two methods to deal with large density gradient flows: particle-copy-delete, variable time-step. By comparison, two method have their own advantages and disadvantages. Each method should be improved by his advantages in future.Although this paper does many researches on DSMC method as a common numerical method, considering that the study of the problem in the initial stage, there is much improvements need to be researched on. Meanwhile, the DSMC method in dealing with complex flow by changing physical models will be the key point in the next stage.