How Underbody Geometric Parameters and Working Clearance Modulate Ground-Effect Flow and Aerodynamic Efficiency of Racing Cars

Ground effect aerodynamics plays a crucial role in the performance of modern racing cars, particularly in the interaction between the underbody geometry and the ground. This article reviews several key parameters related to the underbody and key working clearance that affect the ground effect flow field and aerodynamic efficiency, including ride height, the geometry of the underfloor inlet and Venturi channels, the geometry of the diffuser, and the sealing structures at the floor edges or sides. Special attention is paid to how these parameters affect the mass flow rate, pressure distribution, boundary layer development, flow separation, and the formation mechanism of vortex structures. Existing literature indicates that the most powerful and consistent evidence currently focuses on the coupling effect between ride height and the geometry of the diffuser. Changes in these parameters can trigger different force field patterns, separation states, vortex disintegration, and even lag phenomena in certain configurations. However, results from simplified bluff-body and diffuser models should primarily be interpreted as evidence for ground-effect mechanisms rather than as direct design rules for complete modern racing cars. Cross-research comparisons are also limited by differences in model configuration, Reynolds number, moving ground conditions, force definitions, and reference areas. Therefore, future research should focus more on multi-parameter coupling, consistent dimensionless comparisons, and aerodynamic robustness under dynamic riding heights, wheel wake, yaw, non-uniform intake conditions and other real operating disturbances.