Superfluid Vortex Interactions

Professor Joel Koplik (City College of NY)

We study the interactions between superfluid vortex filaments and rings, with emphasis on annihilation and reconnection events. The calculation is based on efficient numerical solutions of the Gross-Pitaevskii nonlinear Schroedinger equation model of superfluid He~II, so as to include physically reasonable core-scale dynamics. The motivation is firstly to consider the maintenance and generation of vorticity in superfluid flows, and secondly to compare the behavior of superfluids and normal (Navier-Stokes) fluids with regard to the evolution of vortex structures. In general it is found that neighboring vortex filament sections of opposite orientation always annihilate smoothly at the core scale, and otherwise the behavior is very similar to that of normal fluid vortices. Collisions of vortex rings resemble the scattering of elementary particles.