Coherent structures in the wake of a SAE squareback vehicle model

Abstract

The wake of a SAE squareback vehicle model is studied both experimentally and numerically for a Reynolds-number of $ Re_h = 1.0 \hspace{5pt} 10^6 $.The investigation focuses on the coherent structures of the intermediate to largest length and time scales. Flow field as well as base pressure fields are observed for the understanding of the relation between the signals of these quantities. Generalizations and differentiations are made by comparison with the documented behavior of Ahmed or similar vehicle models or three-dimensional bluff bodies. In comparison the vortex shedding acts similar but is restricted to the upper half of the wake of the SAE vehicle model. Due to the localization and phase behavior of the vortex shedding the connection between the base pressure signals and the flow field is weak. However, the pressure signals may be a viable feedback sensor under certain conditions, for example in flow control applications. A flapping of the near wake is identified for the fluctuations of the low frequency time scales.