Interactions of Shedding and Streamwise Vortices in the Transitional Wake of an Asymmetric Coupled Body,

This paper studies the vortex interactions between vortices with different creation mechanisms induced by a simple asymmetric coupled solid model in transitional near wake flow and their effect on the wake region. The asymmetric solid model is created by coupling an angled delta flat plate to one edge of an infinite normal flat plate - This creates an interaction between steady streamwise vortices and periodically shedding spanwise vortices. The flow has a Reynolds number Re = 750 with respect to the normal flat plate. The flow characteristics are investigated for a delta flat plate - normal flat plate chord ratio (CR) of 2 and was chosen to represent an interaction where the streamwise vortex affects the shedding vortices at both edges of the normal flat plate. Although the spanwise shedding vortices are much stronger than the streamwise vortices the interaction of the two vortices results in a highly unstable interaction zone with no spanwise vortex reconnection at the coupled edge, and an unstable and clearly perturbed free edge. A reduced spanwise vortex shedding frequency is observed when compared to the vortex shedding frequency for a normal flat plate of the same chord length. The streamwise vortices lose all coherence in the interaction and all vortices breakdown into rib like structures at the end of the near wake region. To understand the underlying energy transfer due to the vortex interactions a volumetric analysis of the vorticity transport is conducted and a detailed discussion of the results presented herein.