Computational study of flow around a simplified car body

The Ahmed body is a simplified car used in automotive industry to investigate the influence of the flow structure on the drag. Wake flow is two-dimensional for low incidences of the rear slant, then becomes three-dimensional when the angle of the hatchback approaches 30° and reverts to two-dimensional behavior for angles higher than 30° where above this angle, a sudden drop in drag occurred. In this paper, we investigate numerically the flow around the Ahmed body for the base slant angles 25° and 35°. Results are compared with experimental data. The two-dimensional behavior of the flow, for the slant angle 35∘35∘, is well predicted, whereas the transition of the wake to a fully three-dimensional, for the slant angle 25°, is not reproduced. Therefore, the flow around the Ahmed body with 25° slant angle can be considered an open challenge for turbulence modeling.