Evolution of a curved vortex filament into a vortex ring

Abstract

The deformation of a hairpin-shaped vortex filament under self-induction and in the presence of shear is studied numerically using the Biot–Savart law. It is shown that the tip region of an elongated hairpin vortex evolves into a vortex ring and that the presence of mean shear impedes the process. In addition, evolution of a finite-thickness vortex sheet under self-induction is investigated using the Navier–Stokes equations. The layer evolves into a hairpin vortex, which in turn produces a vortex ring of high Reynolds stress content. These results indicate a mechanism for the generation of ring vortices in turbulent shear flows, and a link between the experimental and numerical observation of hairpin vortices and the observation of Falco [Phys. Fluids 20, S124 (1977)] of ring vortices in the outer regions of turbulent boundary layers.

Files

Additional details