Vortex structures in dilute quantum fluids

TL;DR

This paper investigates vortex structures in dilute quantum fluids using the Gross-Pitaevskii equation, analyzing vortex rings, flow past objects, and the effects of surface roughness on critical velocities relevant to superfluid dissipation.

Contribution

It provides new insights into vortex core structures, excitation energies, and how surface roughness influences critical velocities in quantum fluids.

Findings

Vortex ring core structures are characterized and analyzed.

Critical velocity decreases with increasing object size.

Surface roughness reduces the critical velocity for vortex formation.

Abstract

Vortex structures in dilute quantum fluids are studied using the Gross-Pitaevskii equation. The velocity and momentum of multiply quantized vortex rings are determined and their core structures analysed. For flow past a spherical object, we study the encircling and pinned ring solutions, and determine their excitation energies as a function of the flow velocity for both penetrable and impenetrable objects. The ring and laminar flow solutions converge at a critical velocity, which decreases with increasing object size. We also study the vortex solutions associated with flow past a surface bump which indicate that surface roughness also reduces the critical velocity. This effect may have important implications for the threshold of dissipation in superfluids and superconductors.