Characterization of the streamwise vortices and near-wake dynamics in the turbulent flow around the 25° Ahmed body based on SPIV

International audienceAhmed body is considered as a simplified road vehicle, appropriate to study typical swirling structures encounteredin automotive aerodynamics, in particular the two counter-rotating longitudinal vortices produced from the sideedges of the rear window which are responsible for a large part of the aerodynamic drag. Here, we use a movingStereo-PIV facility to characterize experimentally the longitudinal vortices produced at high Reynolds number(Re = 2.8 × 10^6) by a 25° slant angle, involving the formation of a marginal separation bubble over the slantedsurface. A smoke visualization technique suggests the occurrence of a conical vortex breakdown in the near wake,the observed dynamics being reminiscent of that documented in the literature for diverging cylindrical tubes athigh Reynolds number