Novel Hydrodynamic Phenomena in Superfluid 3He

by A. P. Finne et al. arXiv.org E-print Archive, 23 Jun 2006 The superfluid phases of ³He are systems with unique properties. The most interesting ones are revealed under rotation, when different types of topological defects can be seen with NMR measurement. Here we report on new observations in rotating flow. These include (1) the coexistence of continuous vortices (skyrmions) and singular vortices across the interface between two superfluids with essentially different properties, ³He-A and ³He-B, and (2) the analog of the Kelvin-Helmholtz instability for the A-B interface when the two superfluids are sliding with respect to each other without friction. The latter is the first realization of an ideal shear-flow instability, which is not distorted by viscosity. Also, (3) a sharp transition between laminar and turbulent superfluid flow was observed for the first time. As distinct from the transition to turbulence in normal liquids, which is governed by the conventional Reynolds number, the observed transition is controlled by a new velocity-independent parameter. This parameter also modifies the Kolmogorov-Obukhov scaling law of the developed turbulence. Finally, (4) a helically twisted vortex state behind a propagating front of quantized vorticity was observed and identified. This front separates the Landau vortex-free state from the equilibrium vortex state in a rotating container, which imitates the solid-body rotation of a superfluid liquid. Read more