Aerodynamic characterization of rolling wheels at high Reynolds numbers

Complex and unstable phenomena, such as large-scale boundary layer separations, recirculation zones, and three-dimensional vortical structures, characterize the flow around rotating cylinders. These phenomena are even more interesting when the cylinder is rolling on a solid surface, like a wheel on the ground, because the knowledge of the unsteady features of the wake matters for the aerodynamic design of race cars. For this purpose, we investigated the flow past an isolated wheel in different configurations. We focus on the effect of the aspect ratio and the Reynolds number on the wake for values that reflect the actual operating conditions for a race car. We validated our Detached-Eddy simulation by comparing the results with particle image velocimetry measurements. Then, we analyzed the flow by exploiting proper orthogonal decomposition to identify the turbulence characteristics. The simulation showed excellent agreement with the available experimental data and helped highlight the physics of the wake downstream rolling wheels in different operating conditions.