Effects of near wall vortex perturbation in an array on the induced velocity and pressure

Abstract

When stationary streamwise vortices are introduced in a turbulent boundary layer, previous flow visualization studies revealed that the flow can be partially relaminarized. To study this phenomenon, and the wall pressure signature of the vortices for detecting unstable departures from equilibrium in active flow control systems, it is important to understand the behavior of vortices near the wall, as well as their locally-induced velocity and pressure gradients. A relatively simple potential flow field with multiple point vortices is calculated, using the method of images, where for each vortex, a virtual vortex of equal strength and distance from the wall, but with opposite rotation, was introduced in the domain. The induced velocity and coefficient of pressure on the wall are sinusoidal are dependent on the vortex position and the array configuration; i.e., the span of the vortices (i.e., the distance between the vortex cores) and the height of the vortices from the wall. The effects of center-pair vortex perturbation in different directions on the induced velocity and pressure coefficient on the wall was also investigated.