Drag reduction of passenger cars with pushed-in rear door and rear bumper

Abstract

This dissertation studies the drag reduction of passenger cars with pushed-in rear door and rear bumper to improve aerodynamics and thus fuel efficiency. Drag reduction was focused on modifications of the surface at the bottom rear side profile of a passenger car in order to maintain attached flow across the sides of the body and a smaller wake size at the rear of the car. A simplified car model was used to represent a typical passenger car. The flow over the car model was simulated in Computational Fluid Dynamics (CFD) software Star-CCM+ to obtain the drag coefficient. Parametric studies were performed in order to determine the best drag reduction configuration. Significant reduction of drag by 4.7% was achieved with the combination of a pushed-in rear door and rear bumper. Combination of both strategies should be made carefully so that early flow separation will not occur on the side rear bumper.