Wheels aerodynamics and impact on passenger vehicles drag coefficient

The effort of developing a vehicle engages all automotive engineering branches, including aerodynamics. To fulfil the CO2 requirements, the body should be as streamlined as possible. This paper aims to analyse the influence the body shape in the wheels area has on the global CdA parameter, which measures aerodynamic performance. Due to the difficulties encountered in lowering this parameter by conventional means, the paper summarizes a study performed on enclosing the rear wheels opening in a progressive way. Due to accessibility and relative small error between simulation and physical test, the method of computational fluid dynamics (CFD) was used to obtain the results. The main conclusion is that enclosing the rear wheel has an important aerodynamic benefit and does not affect other functions of the vehicle. Careful design of wheel area from an aerodynamic point of view and not only for visual considerations may lead to significant reduction in drag and improvements of vehicle drag coefficient. Based on the positive results, the work will be continued by adapting this idea on commercial vehicles. Although CFD is a good method for developing and optimizing aerodynamic solutions, the results should be validated by physical tests.