Twin-vortex flow physics

Abstract

In this paper, the formation and manipulation of a twin-vortex behind a flat plate and three circular arcs of the same chord as the flat plate have been studied in a water flow channel. The twin-vortex behind the plate and arcs were captured at Reynolds numbers, which are much higher than that for the flow past a circular cylinder. The reverse flow location downstream of the object is found to be at the tip of the vortices. The twin-vortex size is found to be sensitive to the orientation of the object to the incoming flow. Using the curvature effect of the arc, the size of the vortex can be adjusted. By introducing a curvature, the vortex gets elongated. The two vortices in the twin-vortex can be made to assume different sizes by introducing an asymmetry of the object to the incoming flow. The vortex behind the forward edge (left vortex) is always larger than that behind the rear edge (right vortex). For small values of deflection in the range 0°—15°, the difference in the size of the twin vortices is not pre-dominant, but for deflection angles more than 15°, the size difference becomes large. The differential nature of the vortex size is found to be almost independent of the Reynolds number of this study.