Numerical investigation for the influence of the car underbody on aerodynamic force and flow structure evolution in crosswind

To investigate the aerodynamic behavior of underbody structure in crosswind conditions, two numerical simulation models have been developed by using computational fluid dynamics method. First, to validate the accuracy of these models, the wind tunnel experiment of model with simplified flat underbody has been designed. The computationally predicted results of realizable k-e model show consistency with experimental data, and the correlation deviation of aerodynamic force is less than 10%. By using such model, the aerodynamic force and flow field of car under steady crosswind are simulated using underbody structure, and the influence on the aerodynamic characteristic has been analyzed. It can be found that the aerodynamic force increased significantly under different yaw angle. The physical mechanism response has been clearly shown by investigating the flow field around car body by vortices visualization technique. The results of this study can be served as a suggestion for studying the vehicle stability of high-speed under crosswind.