Abstract: Aiming at the problem that the contact computation was complex due to the large mesh size when using single grid method for neighbor search, we proposed a new method based on multigrid. First, the method virtual discretized particle with large ratio of length to diameter (such as long straw particles) into small ones, then the discrete particles were mixed with other particles, and the multigrid method was used to search neighbor. The experimental results show that the method reduces the size of neighbor search grid and the number of neighbor element particles, thus shortens the contact calculation time and improves the calculation efficiency.

Key words: multigrid, ratio of length to diameter, discrete element method, contact calculation