Bursting on straight and curved vortex tubes by Lingbo JI (MIT)

Common vortical wake vortices as generated by aircraft, submarines, and flying and swimming animals often have non-trivial internal shapes and structures, and are subject to perturbations arising from the ambient or self-induced strain fields. In this study we first simulate straight vortex tubes endowed with core-size variations and study their long-time flow evolution. We observe that the differential rotation rates tilt the vortex lines and generate twist waves. The twist waves propagate and their collision leads to a drastic expansion of vortex core, a phenomenon known as vortex bursting. We provide an overview of the evolution and probe the detailed mechanism of bursting. Moreover, we consider vortex tube with non-rectilinear centerlines, in particular, helical vortex tube with small radius-to-pitch ratios and circular vortex rings, and reveal the effects of core-size perturbation on the stability of these vortices and the effects of non-rectilinear centerline on the bursting dynamics and helicity evolution. These findings carry implications for understanding ambient mixing, cavitation and stability of aircraft trailing wakes.