Interplay of laminar and turbulent dynamics in helium superfluids in T → 0 limit

A superfluid in the zero-temperature limit, T → 0, has traditionally been used as the example of a simple inviscid Euler fluid. In superfluid ³He-B below 0.2 Tc vortex flow does not appear to be affected by surface friction or pinning in a smooth-walled rotating cylinder and can thus be studied in almost ideal conditions. Nevertheless, recent measurements and vortex filament calculations display complex interplay between turbulent and laminar responses where the energy and momentum transfers between the ballistic normal excitations and the superfluid condensate become disconnected. While relatively efficient energy transfer provides rapid decay of turbulence, the two orders of magnitude weaker angular momentum coupling leads to a partial decoupling of the initial dynamic response from the external hydrodynamic drive.