Abstract: The traditional cut-paste algorithm is usually unsuccessful in solving the assembly of an overset grid system between slit walls. In order to resolve this problem, two improved methods, the vertex method and the volume method, are presented in this article. The vertex method is based upon the grid cell vertex state and the volume method upon the grid cell size. The two methods change the two-step searching methods of cut and paste to a single step searching method to optimize the hole-surface. The results of the three example cases show that the two improved methods can solve the above problem successfully and they are able to transmit field data between the overset regions correctly. Furthermore, the computational results agree well with the experimental data, the optimization efficiency is higher and the rate of convergence is faster than the cut-paste method. The volume method, compared with the vertex method, can reduce the numerical error caused by the mismatch of grid sizes in the overset grid system, and obtain a better result and accuracy.

Key words: computational fluid dynamics, overset grids, cut-paste algorithm, hole-surface optimization, slit wall