Application of self-adaptive voronoi grid technology in dsmc method

Paper number

IAC-06-C4.P.3.05

Author

Mr. Hou Fenglong, Beijing University of Aeronautics and Astronautics, China

Coauthor

Mr. Jianhua Zhang, Beijing University of Aeronautics and Astronautics, China

Coauthor

Mr. He Bijiao, Beijing University of Aeronautics and Astronautics, China

Coauthor

Prof. Guobiao Cai, Beijing University of Aeronautics and Astronautics, China

Year

2006

Abstract

For rarefied gas dynamics problems, when the scale length of the gradients of the macroscopic parameters is of the same order as the mean free path, the Navier-Stokes equations of continuum gas dynamics would fail. The Direct Simulation Monte Carlo (DSMC) method is an effective way to solve rarefied gas dynamics problems. The DSMC method, with tracing and sampling of particles as its main characteristic, demands that the cell dimension should be of the same order as the mean free path. Therefore the self-adjustment of cells is necessary for DSMC method. 
As for common grids in the DSMC method, Cartesian grid has high computation efficiency but low adaptability for complex geometric boundaries, while structured grid is not suitable for self-adaptive calculation, and unstructured triangle grid has low computation efficiency and could cause particle losing.
Voronoi grid is quite different from the common grid in DSMC method, for it is based on the theory of Dirichlet tessellation and Voronoi diagram. Voronoi cell is defined by its characteristic point. The peculiar mapping arithmetic between the particle system and the Voronoi cells is suitable for the sampling process in DSMC method. Voronoi grid technology could deal with complex geometric boundaries and support self-adaptive DSMC calculation.
The self-adaptive Voronoi grid technology was used in a DSMC calculation of rarefied gas flow passing a cylinder. The results proved the self-adaptive capability of Voronoi grid technology in DSMC method. In order to compare the efficiency between the Voronoi grid and the common grids in DSMC method, a DSMC calculation of rarefied gas flow passing a vertical baffle was carried out. Based on the above researches, self-adaptive Voronoi grid technology was applied to a two dimension micro-nozzle flow problem. Compared with the literature results, the validity of self-adaptive Voronoi grid technology was proved.
This paper is an instructive work of applying self-adaptive Voronoi technology to DSMC method.

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