The Impact of Tire Shoulder Radius on the Aerodynamics of a Rotating Isolated Wheel

Abstract This study investigates the influence of tire shoulder radius and Reynolds number on the aerodynamics of an isolated rotating wheel in contact with a moving ground, representative of automotive applications. Four shoulder radii, ranging from a sharp corner (R/D = 0) to a rounded edge (R/D = 0.1), were examined across a Reynolds number range (ReD) from 8.38 × 105 to 1.95 × 106. Numerical simulations were performed using IDDES and the k-omega SST turbulence model. Wheels with larger R/D exhibited elevated Reynolds number sensitivity, however the impact of R/D variation overshadows the impact of the Reynolds sensitivity. Increasing the shoulder radius significantly reduces both drag and lift, primarily due to improved flow attachment and a consequent reduction in wake size. Larger shoulder radii delayed the formation of the upper counter-rotating vortex pair and reduced the strength of the “jetting” ahead of the contact patch. This research provides insights into isolated wheel aerodynamics and offers guidance for optimizing tire geometry to improve aerodynamic performance.