Large-scale superfluid vortex rings at nonzero temperatures

TL;DR

This paper models large-scale superfluid vortex rings in helium, demonstrating that the interaction with normal fluid vortex rings is crucial for their coherence at nonzero temperatures, impacting superfluid turbulence understanding.

Contribution

It introduces a numerical model showing the importance of superfluid-normal fluid vortex interactions in large-scale vortex ring coherence at finite temperatures.

Findings

Normal fluid vortex rings are essential for superfluid vortex coherence.

Superfluid-normal fluid vortex interactions influence turbulence dynamics.

The model aligns with experimental observations of vortex structures.

Abstract

We numerically model experiments in which large-scale vortex rings - bundles of quantized vortex loops - are created in superfluid helium by a piston-cylinder arrangement. We show that the presence of a normal fluid vortex ring together with the quantized vortices is essential to explain the coherence of these large-scale vortex structures at nonzero temperatures, as observed experimentally. Finally we argue that the interaction of superfluid and normal fluid vortex bundles is relevant to recent investigations of superfluid turbulence.