Speaker Institution : Department of Physics - University of Maryland
Title : Helicity Dynamics
Abstract: Helicity is a conserved quantity that arises in ideal fluid flows and ideal magnetohydrodynamic magnetic fields. I will first review the background theory of Helicity in those two cases, a famous paper by Finn and Antonsen, and another by Keith Moffatt. I will follow by covering some basic phenomenology of quantized vortices, reconnection, and Kelvin waves, and background of our visualization studies in superfluid helium. These topics lead into a discussion of what has been done, what we know, and what is predicted about Helicity dynamics. Some observations about the untangling of vortices via reconnection lead to predictions regarding the Helicity we are exploring experimentally. Some puzzles and questions about the role of invariants like the Helicity in the Gross-Pitaevskii (nonlinear Schrodinger) equation play a role in thinking about this phenomenon.