Effect of Vortex Street on Mixing Enhancement in a Mixing Layer

Abstract

In this paper, the effect of vortex street on increasing mixing in a mixing layer is investigated numerically. The end of the splitter plate is made into square cylinder shape in order to set a square cylinder in the mixing layer for generating the vortex street. The vortex street is formed behind the cylinder in the initial stage of the mixing layer when the top and bottom streams flow over the square cylinder. The large scale vortices in the vortex street are utilized to enhance mixing of two different-speed streams in the mixing layer. The reason of the asymmetry of the vortex street is explained. The case of a mixing layer between two walls is also studied numerically. The results of numerical simulation show that small velocity difference between two streams is good for mixing enhancement in the confined mixing layer. The vortex street has a good effect on mixing enhancement in a mixing layer.