Viscous diffusion of vorticity using the diffusion velocity concept

Abstract
The primary purpose of this paper is to provide an evaluation of the diffusion velocity concept with regard to its ability to predict the diffusion of vorticity near moving walls as well as in unbounded two-dimensional space. We also briefly outline a "bi-zonal" wall model which utilizes the diffusion velocity concept and is compatible with vortex methods. A primary goal of this model is to minimize the number of vortices generated on the surface at each time step while achieving good resolution of the vorticity field near the wall. We have generated results for an initially square patch of vorticity in an unbounded domain, an impulsively started flat plate, an oscillating flat plate, uniform flow over a semi-infinite flat plate, and flow over a wedge. The simulations are found to give excellent results when compared to classical solutions of these problems.