Evolution of coupled Gaussian vortex systems in helium II

Abstract

We have investigated the evolution of the normal and superfluid flow in helium II using the two-fluid Hall–Vinen–Bekharevich–Khalatnikov equations. We found that closely matched Gaussian vorticity distributions form in both the superfluid and the normal fluid and decay together with a viscous time scale that is set by the total fluid density and not by the density of the normal fluid alone. This calculation suggests that the normal fluid and superfluid can have velocity fields which are strongly coupled together so that the two fluids behave as a single fluid.