Impact of a vortex ring on a density interface using a regularized inviscid vortex sheet method

A new, fully three-dimensional, vortex-in-cell method designed to follow the unsteady motion of inviscid vortex sheets with or without small (Boussinesq) density discontinuities is presented. As is common in front-tracking methods, the vortex sheet is described by a moving, unstructured mesh consisting of points connected by triangular elements. Each element carries scalar-valued circulations on its three edges, which can be used to represent any tangent vector value and in the present method represent the element's vorticity. As the interface deforms, nodes and elements are added and removed to maintain the resolution of the sheet and of the vortex sheet strength. The discretization and remeshing methods allow automatic, near-perfect conservation of circulation despite repeated stretching and folding of the interface. Results are compared with previous experiments and simulations. Similarities are observed between the present simulations and experiments of a vortex ring impacting a wall.