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

James Venning (1) , David Lo Jacono (1, 2) , David Burton (3) , Mark C. Thompson (1) , John Sheridan (1)

1 Fluids Laboratory for Aeronautical and Industrial Research - FLAIR (Victoria, Australia)
2 IMFT - Institut de mécanique des fluides de Toulouse
3 Department of Mechanical and Aerospace Engineering [Victoria]]

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.

Mots clés: Ahmed body; PIV; Wake

Domaines: Mécanique des fluides [physics.class-ph]; Milieux fluides et réactifs

James Venning, David Lo Jacono, David Burton, Mark C. Thompson, John Sheridan. The effect of aspect ratio on the wake of the Ahmed body. Experiments in Fluids, 2015, vol. 56 (n° 6), pp. 1-11. ⟨10.1007/s00348-015-1996-5⟩. ⟨hal-01167075⟩