Aerodynamic Simulation of a Standalone Round and Deforming Treaded Tire 2021-01-0948

For a typical passenger ground vehicle, the rotating treaded tires and wheel housings typically account for up to 25% of the total vehicle aerodynamic drag. Due to the importance of tires and their treads to the overall vehicle aerodynamics, it’s critically important for aerodynamics departments to have accurate simulations that can predict the effects of rotating tires. Accurate prediction of flow around a tire is a complex phenomenon and is affected by details of tire features such as tread pattern, air pressure, and tire deformation. In particular, the physics of the tire treads spatial movement and deformation (i.e. expansion, contraction, sidewall bulge, and squeezing of airflow) as the tires rotate and come in contact with ground, especially around the contact patch, is vitally important in determining accurate wheel wakes, underbody flow, and the overall wake of the vehicle. Recent developments have expanded an existing capability for simulating solid body motion to simulating a true deforming tire with accurate representation of tread motion, deformation, contact patch and sidewall bulge. The current study incorporates a Lattice Boltzmann method (LBM) based CFD solution using an Immersed Boundary method (IBM) to simulate and validate a realistically rotating and deforming standalone treaded tire. For ease of use, the solution doesn’t require the user to prescribe the motion and deformation of the tire, but rather automatically calculates the changes in time from a single stationary representation of the deformed tire. Simulations using this new capability demonstrate significant improvements over previously published results, which used round rotating treaded tires. Results are validated against previous wind tunnel experimental measurements. Further discussion on the effect of tire loading (i.e. bulge deformation) on wake results is also presented and discussed.