Grid independence and scheme research for simulating aerodynamic drag of MIRA model

Grid scheme is discussed, which has a great influence on the result of numerical simulation of vehicle aerodynamic drag. Based on current adequate computing resource, the notchback MIRA model was built, and tetrahedral mesh and polyhedral mesh were separately generated. Then grid refinement was respectively performed around the model and at the rear of the model and sufficient grid number was guaranteed. Numerical grid-independent results were obtained, and variation tendency of drag coefficient with the grid number growth was summarized. In addition, the numerical simulation results were compared with those of wind tunnel test. The results show that once grid refinement is implemented, drag coefficient is significantly decreased. The decline curve of drag coefficient gradually levels off with the increasing grid number and grid-independent results can be gained when the grid number increases. The final drag coefficient is less than the experimental data of wind tunnel test and there is an error between them.