Aerodynamic characterization of the wake of an isolated rolling wheel

• Experimental and numerical characterization of the wake of an isolated wheel.
• CFD is able to reproduce the flow topology and its unsteady behaviour.
• New insight of the unsteady evolution of the wake.
• Vortex dynamics analysis and effect on aerodynamic coefficients.

The flow around the wheels of road vehicles exhibits complex unsteady 3D phenomena, including massive boundary layer separations, recirculation areas and 3D vortical structures. Although the mechanisms generating the wake main vortices have been identified, their exact topology is still indeterminate and a description of their unsteady evolution has not yet been proposed.The aim of this paper is to characterize the structure and unsteady motion of an isolated wheel wake. For this purpose, wind tunnel investigations have been carried out with a smooth rotating wheel in contact with a moving belt and compared to URANS simulations based on the geometry used for experiments.CFD calculations appeared to have successfully predicted the main features of the flow. Particle Image Velocimetry and hot-wire anemometry measurements coupled with numerical simulation results enabled the origin and the nature of the main vortical structures in the near-wake to be confirmed and their unsteady behaviour to be investigated. The results show good agreement with previous knowledge and provide new insight into the unsteady features of the wake.