The effect of aspect ratio on the wake of the Ahmed body

Abstract

This paper seeks to further elucidate the wake of the Ahmed body by investigating how the time-averaged flow structures vary with frontal aspect ratio. High-resolution particle image velocimetry results are provided for eight different width Ahmed geometries at Re = 3 × 10^4. It is shown that the narrower the body, the greater the downwash over the back slant, meaning the flow remains more attached. At a critical aspect ratio ( AR = 1.9), the flow downstream changes. The separation over the back slant is shown to be affected by the AR, and this in turn has a significant effect on the circulation in the c-pillar vortices.