A comparison of normal fluid and superfluid vorticity in Taylor-Couette flow of helium II

Abstract

We have compared the normal fluid vorticity and the superfluid vorticity in Taylor-Couette flow of He II. We have found that when the normal fluid vorticity is large the method of free energy minimization correctly predicts the superfluid vorticity to be nearly equal to the normal fluid vorticity. When the normal fluid vorticity is small, however, free energy minimization is no longer valid. The lowest free energy state becomes a limit which the system approaches but never quite achieves. The evidence suggests that the dynamics of vortex growth and decay and the presence of residual vorticity determine the superfluid vortex state.