Effect of the tires position with respect to the tire-belts on aerodynamic coefficients

The objective of this thesis is to shift the focus towards the precise positioning of the wheels concerning the rotational airflow within a wind tunnel. Previous studies and research have revealed the significant influence that wheel positioning exerts on both aerodynamic coefficients and emissions. To investigate this impact, two distinct methodologies will be employed in an attempt to establish the most robust correlation between real-world observations and virtual simulations. In today’s computing landscape, the available resources enable automotive companies to achieve a strong correlation between numerical Computational Fluid Dynamics (CFD) simulations and wind tunnel experiments. CFD simulations, in comparison to wind tunnel tests, offer cost-effectiveness and flexibility, allowing the examination of different models without the need for constant prototype changes, along with the exploration of various flow field attributes. However, certain scenarios, such as simulating rotating wheels, continue to be areas where the correlation with wind tunnel tests remains under scrutiny. In the initial chapters of this thesis, a comprehensive overview of fluid dynamics concepts will be provided, with particular emphasis on the Navier-Stokes equations and turbulence models, including their relevance to the study at hand. Subsequently, concepts of vehicle aerodynamics will be introduced, with a primary focus on airflow around tires. Following this, the fundamentals of computational fluid dynamics will be delved into, detailing its tools and methodologies, while preparing the ground for the experimental analysis. The experimental part of this research was conducted at the Wind Tunnel of CRF (Centro Ricerche Fiat), a subsidiary of Stellantis, located in Orbassano (TO). The commercial software STAR-CCM+® will be used for numerical simulations, and ANSA for pre-processing operations. ANSA is an advanced multidisciplinary CAE pre-processing tool that offers comprehensive functionality, facilitating the transition from CAD data to solver-ready input files within a unified environment. In the concluding chapters, the results derived from both methodologies will be presented, aiming to have a discussion regarding the correlation of the discovered aerodynamic coefficients, leading to a final conclusion of the work.