Vortex simulation of turbulent mixing layers

Abstract

We present here a brief survey of vortex-dynamical simulations of the plane mixing layer using different forms of vortex elements. Points and blobs, which have been widely used in the past, suffer from irregular evolution of the vortex sheet approximating the shear layer, and the rather long time-averaging required to obtain meaningful statistics. A technique recently proposed by the authors, using vortex arcs or sheet elements, has been found to be helpful in avoiding these difficulties. In particular, this technique avoids the singularity in induced velocity associated with point vortex techniques, and is therefore in no need of any form of the "desingularization" that is often introduced in the latter. New results for excited mixing layers using the vortex sheet element model are presented, and are shown to be in good agreement with experimental observations.