The Two-Fluid Theory for Superfluid Hydrodynamics and Rotational Motion
arXiv:2505.08826
Abstract
The two-fluid theory for superfluid hydrodynamics is derived from the fountain pressure result that condensed bosons move at constant entropy and are driven by the chemical potential gradient. Explicit results for He show that the superfluid has vorticity, which is consistent with measured data but inconsistent with Landau's principle that superfluid flow is irrotational. The macroscopic wavefunction is criticised.
14 pages. v3 now with rotational motion. v4 criticises irrotational requirement. v5 critically reviews path integral simulation results for condensation. v6 sections on irrotatinal vortices, quantized circulation, and the macroscopic wavefunction have been added