The Two-Fluid Theory for Superfluid Hydrodynamics and Rotational Motion

TL;DR

This paper derives a two-fluid hydrodynamic theory for superfluids from fountain pressure principles, revealing superfluid vorticity and challenging traditional irrotational flow assumptions, with specific insights into helium-4 behavior.

Contribution

It introduces a novel derivation of superfluid hydrodynamics from fountain pressure, highlighting superfluid vorticity and critiquing the macroscopic wavefunction concept.

Findings

Superfluid helium-4 exhibits vorticity, contrary to traditional irrotational flow assumptions.

The derived theory aligns with experimental data on superfluid motion.

The macroscopic wavefunction concept is critically examined and challenged.

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 $^4$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.