WANG Chuncai, CHENG Jia, JI Linhong, LU Yijia, SUN Yuchun, LIN Jia
Traditional direct simulation Monte Carlo (DSMC) models using rectangular elements inevitably have errors when dealing with complex computational domain boundaries. Unstructured grids are able to adapt to any complex geometric shape but are rarely applied because of the highly disordered topological structure, complex calculations and low execution efficiency. This paper describes a particle trajectory tracking algorithm based on an unstructured Delaunay triangle mesh. The computational domain is divided into various rectangular regions with only a small number of triangular elements with the particle trajectory tracking achieved by first searching the rectangular regions and then the triangular elements. The algorithm is used in a two-dimensional DSMC program with the results comparing well with results in the literature. The DSMC program is then used to predict the flow field in a showerhead aperture with argon as the neutral reference gas with an inlet pressure of 200 Pa and an inlet temperature of 300 K. The results show that the radial velocity and temperature distributions are less affected by the showerhead aperture than by the radial pressure distribution. Increasing the showerhead aperture improves the radial velocity and temperature distribution uniformity, while decreasing the showerhead aperture improves the radial pressure distribution uniformity.
