Optimisation of numerically modelling rotating wheels in CFD

Vehicle wheels can contribute up to 30% of total vehicle aerodynamic drag which directly increases fuel consumption and emissions, highlighting the importance of accurate aerodynamic modelling. Flow structures created by detailed rotating wheels remain difficult to predict and analyse due to geometrical complexities and limitations of experimental studies, with previous numerical investigations often simplifying the geometries of vehicle wheels. A comprehensive numerical investigation was conducted using various techniques to model wheel rotation on the DrivAer model with standard wheels and detailed wheels. It was found that modelling rotation produced lift and drag reductions of up to 150% and 6.9% respectively with the standard wheel compared to the static wheel case, and reductions of up to 272% and 9.3% respectively for the detailed wheel. Key differences in flow structures were observed between static and rotating cases and also between the various rotation modelling techniques, with characteristic vortices and flow separation varying in position and magnitude greatly. The difference in lift and drag prediction between different rotation modelling techniques varies as much as ΔCL = 0.056 and ΔCD = 0.022 respectively for the detailed wheel. Unsteady simulations also revealed transient features which were not captured by the steady-state models.