A Vortex Ring Interacting with a Vortex Filament and its Deformation Near the Two-Dimensional Stagnation Point

In this paper the interaction between vortex filaments and vortex rings and the deformation of vortex rings near the two-dimensional stagnation point are simulated by a three-dimensional vortex method (Shirayama etal. 1985, Leonard 1985). The two problems are respectively concerned with the effect of free-stream turbulence on turbulent plane mixing layers (Pui & Gartshore 1979) and the production of turbulence by the vortex stretching near saddles associated with large-scale coherent structures(Cantwell & Coles 1983, Kiya & Matsumura 1985). We assume that the first step to understand the free-stream turbulence effects is to study the interaction between a vortex ring and a vortex filament and that the process of deformation of a vortex ring gives us a clue to understand physical processes occurring near the saddles.