Generation and evolution of vortical structures in bluff body wakes

Abstract

A direct numerical simulation has been used to study the generation and evolution of streamwise vortices in the near wake of a circular cylinder at a Reynolds number of 300. It is found that new streamwise vortices are generated due to the stretching induced by the spanwise vortices of streamwise vorticity associated with the older streamwise vortices. Furthermore, even though the spanwise vortices develop significant spanwise distortions due to the action of the streamwise vortices, entrainment of vorticity from the core of the spanwise vortices into the so called 'braid' region is not observed. The evolution of the spanwise vortices is also followed in detail and this provides further insight into the interaction of the various vortical structures in the near wake. (Author)