Francois Frenkiel Award Talk: Universal and nonuniversal aspects of vortex reconnections in superfluids *

Vortex reconnections play a fundamental role in fluid dynamics: understanding this mechanism sheds new light on how energy is transferred through scales and how topological fluid dynamical properties are modified. In superfluids, vortices are topological defects with quantised values of circulation. Despite the lack of dissipation, quantised vortices do reconnect in superfluids because the fluid density vanishes at the vortex core. 

We will explain how reconnection events occur in the Gross—Pitaevskii equation, a general model of superfluid, studying different vortex configurations. Through asymptotic theory and numerical simulations we will demonstrate what are the universal and non-universal aspects of superfluid vortex reconnections. Finally, we will present some recent results on how vortex energy is dissipated into sound excitations during a reconnection event.