Interactions between normal-fluid and superfluid vortex rings in helium-4

By employing both vortex-dynamical and self-consistent Navier-Stokes methods of analysis, an investigation of interactions between normal-fluid and superfluid vortex rings in helium-4 is performed. It is shown that, under the influence of normal-fluid vortices, superfluid vortices grow in size in order to match the size of the latter. In turbulence, this mechanism hints to a tendency towards scale-to-scale energy equipartition in the spectral regimes corresponding to the inertial-range in the normal-fluid. Yet, the analysis shows that the induced superfluid vorticity is not trapped by the cores of the normal-fluid vortices, and, consequently, there is no strong correlation between normal-fluid and induced superfluid vorticity patterns. Hence, there is no significant vortex locking effect.