Diffusion of an Inhomogeneous Vortex Tangle

TL;DR

This paper investigates the diffusion behavior of inhomogeneous vortex tangles in superfluid turbulence through numerical simulations, finding very small diffusion constants consistent with theoretical expectations and discussing implications for low-temperature experiments.

Contribution

It introduces a numerical study of vortex tangle diffusion using the vortex filament model and compares results with a generalized Vinen equation, highlighting the small diffusion constant.

Findings

Diffusion constant is very small, aligning with theoretical predictions.

Numerical results match the generalized Vinen equation.

Implications for superfluid turbulence experiments at low temperatures.

Abstract

The spatial diffusion of an inhomogeneous vortex tangle is studied numerically with the vortex filament model. A localized initial tangle is prepared by applying a counterflow, and the tangle is allowed to diffuse freely after the counterflow is turned off. Comparison with the solution of a generalization of the Vinen equation that takes diffusion into account leads to a very small diffusion constant, as expected from simple theoretical considerations. The relevance of this result to recent experiments on the generation and decay of superfluid turbulence at very low temperatures is discussed.