Inviscid axisymmetrization of an elliptical vortex

The inviscid evolution of elliptical, nonuniform vorticity distributions is studied computationally using a high resolution Lagrangian (vortex) method with minimal numerical dissipation. The simulations reveal that the vortices evolve, through a process of filamentation, to a configuration consisting of a vortex surrounded by weak filamentary structures. The shape of the final configuration depends on the profile of the initial vorticity distribution. For the same ellipticity, relatively smooth profiles evolve to axisymmetric vortical structures, whereas sharper initial vorticity distributions result in robust nonaxisymmetric configurations. A systematic convergence study is conducted to establish the accuracy of the method for long time inviscid simulations. To further assess the issue of axisymmetrization we compare our results with related numerical and experimental studies. (C) 1997 Academic Press.