Numerical and experimental investigations of rotating wheel aerodynamics on the DrivAer model with engine bay flow

Wheel design and wheel rotation have been identified to be key factors influencing the overall aerodynamic performance of passenger cars. Hence, wheel aerodynamics has been the topic of various studies over the past few years. Recently, vehicle manufacturers have moved towards time-resolving CFD simulation methods. Therefore, a trend towards resembling the physical effect of wheel rotation by utilizing the Sliding Mesh Method can be observed in academia and the industry. The first part of the presented paper shows the results of CFD simulations using the Sliding Mesh Method on two generic test cases employing the Delayed Detached Eddy Simulation turbulence model. A rotating cylinder is investigated as well as a rotating wheel geometry, both in ground contact and lifted from the ground. The results show dependencies on the solution algorithm and the background turbulence model applied within the RANS region of the Delayed Detached Eddy Simulation model. The prediction accuracy of the CFD setup is assessed by comparing the results to experimental results on the rotating wheel geometry with ground contact obtained in a model scale wind tunnel. The second part of the paper focuses on the influence of the rim design on the aerodynamics of a full vehicle. Four rim geometries are investigated regarding their aerodynamic influence on the DrivAer reference body by CFD simulations using the Sliding Mesh Method. The DrivAer has recently been updated to include an engine bay geometry. This new version of the DrivAer is used for the presented study because the engine bay flow is expected to have a considerable influence especially on the flow around the front wheels. The simulation results are compared to experimental results obtained on a 1:2.5 scale model of the DrivAer with engine bay flow and are in good agreement.