On the Aerodynamics of Ground Vehicles Subjected to Crosswind Gust and Its Shape Dependence

Unsteady aerodynamic forces acting on road vehicles subjected to gusty crosswind were investigated, with the special focus on the dependence of the aerodynamic response on the upper and underbody shapes. Large-eddy simulation technique was adopted to investigate the relationships between the transient aerodynamics forces and flow structures around the vehicles. Hatchback and sedan type vehicles were considered to discuss the upper-body effects, while the same sedan vehicles with different underbody shape were focused for the under-body effects. It was found that the sedan vehicle shows larger yaw-moment peak than the hatchback vehicle and in this context, the former is supposed to be more unstable to the crosswind. Concerning the underbody shape, the responding yaw moment is more peaked in the flat floor case than in the rugged floor.