Aerodynamics has become increasingly important these days in the design of automobiles due to the increased constraints placed on the emissions. In the past the focus has been primarily on the shaping of the upper body. However, due to practical requirements, further scope of improvements to the upper body has been greatly reduced. The focus has thus shifted towards the optimization of the underbody which includes the wheel and the wheelhouse. The contribution of the wheel and the wheelhouse to the total drag and lift coefficient of a body has been estimated at 30\% and 40\% respectively. Therefore, understanding the behavior of the flow in the wheelhouse would potentially result in reducing the drag coefficient of an automobile.

In the present study, the wheelhouse flow has been investigated experimentally using Particle Image Velocimetry (PIV). A generic simplified car body with a wheel and a wheelhouse has been designed and used for this purpose. The study has been done for a rotating wheel and stationary ground configuration. Planar PIV and Stereo PIV have been used to study the flow inside the wheelhouse and in the wake of the wheel respectively. The study was undertaken for the Reynolds number, based on wheel diameter, of 9000 and 72000. Measurements were taken at planes inside and outside the wheelhouse as well as upstream and downstream of the wheel. In addition to providing data for the Large Eddy Simulation (LES), the results from the PIV measurements showed that the behavior of the flow depended on the Reynolds number. Velocity profiles in the wake of the wheel highlighted a three dimensional flow in the wheelhouse.

Finally, the effect of a Vortex Generator (VG) on the flow was investigated. The VG was found to have an effect at the low Reynolds number wherein the flow inside the wheelhouse and in the underbody was found to be quite different compared to the configuration without a VG.