Turbulent near wake behind a partially grooved circular cylinder

The near wake of a partially V-grooved circular cylinder is investigated The flow over the smooth half is within the high subcritical regime, while that over the grooved half is within the transcritical regime. Secondary and Strouhal vortices are found in the near wakes of both halves. The formation of the secondary vortices, due to the separated shear layers, is coupled to the formation of the Strouhal vortices. These secondary vortices of the two halves are of the horse shoe type. On the grooved half another type of secondary vortices is found to be caused by the flow over the triangular blunt end of the V grooves.