Quantum turbulence in coflow of superfluid ${}^4$He

TL;DR

This paper numerically investigates quantum turbulence in superfluid helium-4 coflow within a square channel, revealing inhomogeneous vortex distributions and a transition from three-dimensional to two-dimensional vortex configurations.

Contribution

It introduces a numerical simulation of coflow quantum turbulence with inhomogeneous vortex distributions, highlighting vortex accumulation and dimensional transition.

Findings

Vortices tend to accumulate on the surface of a cylinder.

Vortex configuration transitions from 3D to 2D.

Vortices are distributed inhomogeneously in coflow.

Abstract

We study numerically nonuniform quantum turbulence of coflow in a square channel by the vortex filament model. Coflow means that superfluid velocity $\bm{v}_s$ and normal fluid velocity $\bm{v}_n$ flow in the same direction. Quantum turbulence for thermal counterflow has been long studied theoretically and experimentally. In recent years, experiments of coflow are performed to observe different features from thermal counterflow. By supposing that $\bm{v}_s$ is uniform and $\bm{v}_n$ takes the Hagen-Poiseiulle profile, our simulation finds that quantized vortices are distributed inhomogeneously. Vortices like to accumulate on the surface of a cylinder with $\bm{v}_s \simeq \bm{v}_n$. Consequently, the vortex configuration becomes degenerate from three-dimensional to two-dimensional.