Influence of wheel rotation and tire geometry details on the numerical prediction of vehicle aerodynamics under crosswind conditions

• The effect of yaw angle on the aerodynamics of a full-scale, detailed vehicle is investigated. • The influence of detailed tire geometry and wheel rotation on the yaw-angle dependency of vehicle drag is clarified. • Guidelines for selecting CFD setups in the early stages of vehicle aerodynamic development are established. Reducing aerodynamic drag is essential for improving vehicle energy efficiency. To reflect real-world conditions, it is important to consider crosswinds in addition to zero-yaw conditions. Tires and wheels contribute to approximately 25 % of total vehicle drag, making accurate modeling crucial. Numerical simulations help in understanding the complex airflow around these components, especially under deformation from ground contact and rotation. Although various methods have been proposed, most previous studies have focused on zero-yaw conditions, with limited attention to crosswind effects. This study investigated how tire shape details and wheel rotation modeling affect yaw-dependent drag and flow characteristics. Three simulation setups, differing in tire geometry and rotation method, were tested at yaw angles of 0°, 2°, and 5° and compared with wind tunnel data. The results show that both the tire shape and rotation approach significantly influence the yaw dependency. The impact was particularly notable when the wheel rotation method was changed from the rotating wall boundary condition to a sliding mesh method, which better captured the spoke-induced flow blockage at the wheel opening, thereby altering the total pressure deficit and wake crossflow. This effect is essential for predicting the yaw angle dependency of drag and flow characteristics derived from the wind tunnel results. These findings highlight the importance of selecting appropriate tire modeling and rotation strategies to improve the prediction accuracy of aerodynamic drag under realistic driving conditions. The results obtained from these novel viewpoints offer valuable insights for improving aerodynamic simulation practical strategies while optimizing in early-stage vehicle aerodynamic design efficiency.