This conference paper was submitted for presentation at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

As the automotive industry increasingly shifts toward electrification, reducing vehicle drag becomes crucial for enhancing battery range and meeting consumer expectations. Additionally, recent European regulations require car manufacturers to provide reliable drag data for vehicles as they are configured (e.g. WLTP, GHG Phase 2). Among the factors influencing vehicle drag, the interaction between tire wakes and the overall vehicle aerodynamics is critical. To improve the performance of designs, it is essential to identify which tire features have a stronger influence on the flow field. While physical testing enables manufacturers to evaluate the aerodynamic effects of tires, isolating the specific impacts of contact patch and bulge deformations is challenging because these features evolve together under load. Computational Fluid Dynamics (CFD) simulations offer a unique capability to decouple and independently analyse these deformation effects. This study investigates the aerodynamic impact of realistic tire deformation parameters, focusing on bulge and contact patch deformations, using Computational Fluid Dynamics (CFD) simulations performed using the Lattice-Boltzmann method. The simulation setup, using a standalone tire model, was validated against experimental results in prior research. Given the complexity of the flow structures in the tire wake, a vortex identification algorithm based on the Gamma-2 criterion, combined with a single-link clustering method, was employed to examine vortex behaviour and downstream wake development. The unsteady nature of the wake required a transient analysis to better understand the influence of deformation parameters on vortex shedding dynamics. The results identify the deformation parameters that most significantly influence the flow field and classify them into two primary groups based on their effects on wake evolution: those that induce wake contraction and those that promote wake expansion. The analysis of the vortex behaviour shows consistent trends that characterize both the contraction and the expansion of the wake, while transient analysis highlighted how these features influence unsteady vortex shedding and its implications for wake width development.