Experimental analysis of car drag reduction through contour bump application

The study explores the impact of aerodynamic drag on vehicle performance, focusing on its reduction to enhance fuel efficiency and stability. A NOAH car model was analysed using both numerical simulations and experimental tests, featuring various rooftop contour bump configurations. Eleven 3D designs, including the base model, were simulated to assess airflow, with results validated through wind tunnel experiments using 3D-printed models. Drag force (FD) and drag coefficient (DC) were calculated for each configuration. The most effective designs, featuring eight, four, and three streamwise bumps, achieved drag reductions of 6.31%, 5.94%, and 5.76%, respectively, with experimental results closely aligning, showing a maximum deviation of 3.27%. This reduction corresponded to fuel consumption decreases of 3.79% in simulations and 3.67% in experiments, so using a bump to the rear roof of the car can reduce almost 770 ml of fuel per 500 km. The findings demonstrate the potential of contour bumps in optimising vehicle aerodynamics without altering the car's design.