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Tuesday, December 04, 2012
1:00 PM - 2:00 PM
CNLS Conference Room (TA-3, Bldg 1690)

Postdoc Seminar

Some Motions of Vortices in Superfluids

Cecelia Rorai
National Center for Atmospheric Research

Quantized vortices in superfluids are mobile and interacting topological defects which cannot be removed by simple diffusion. Two non-parallel quantized vortices form annihilating or propagating vortex dipoles in two dimensions, while, in three dimensions, they can cross and reconnect by exchanging tails. This mechanism was conjectured theoretically by Feynman in 1955, and observed experimentally by Bewley et al. in 2008. The nature of vortex reconnection is quantum mechanical, involving the atomically thin vortex cores, but it also influences the large scale dynamics of quantum turbulence, causing a tangle of quantum vortices to change topology, evolve in time, and eventually decay. We study the dynamics of vortices in superfluid helium by means of the Gross-Pitaevskii (GP) equation. The initial conditions are analyzed carefully, different geometries are considered, and particular attention is paid in minimizing the initial total energy. Following this approach a more general characterization of vortex dipole behavior is found and a new family of reconnection fixed points is discovered.

Host: Susan Kurien, T-5,