Abstract: It's very difficult to simulate the move of valve in the 3-d simulation of air motion inside the cylinder of engine, because the valve is an obs truct to the flows and moves by certain rule, It's very important to simulate the flow of S. I engine, including the valve and so on. In this thesis, a technology of grain simulation was used. In this technology, grids of valves were not created separately but were simulated by using lots of grains. The idea was that , the grains move according to the rule of valves, and the gas stops moving as the grains lock in the grids. This technology is  simple and appropriate to simulate the valves.

Key words: 3- D calculation, 3- D flow, gasoline engine