Enhancement of intermittency in superfluid turbulence

TL;DR

This paper investigates how superfluid turbulence in helium-4 exhibits enhanced intermittency at certain temperatures due to mutual friction, using shell model simulations to predict stronger intermittency effects in an intermediate temperature regime.

Contribution

It introduces a shell model simulation approach to predict increased intermittency in superfluid turbulence at specific temperature ranges where normal and superfluid components are comparable.

Findings

Enhanced intermittency observed in the intermediate temperature regime.

A proposed bridge relation links effective and classical scaling exponents.

Experimental validation suggested at accessible temperatures and Reynolds numbers.

Abstract

We consider the intermittent behavior of superfluid turbulence in $^4$He. Due to the similarity in the nonlinear structure of the two-fluid model of superfluidity and the Euler and Navier-Stokes equations one expects the scaling exponents of the structure functions to be the same as in classical turbulence for temperatures close to the superfluid transition $T_\lambda$ and also for $T\ll T_\lambda$. This is not the case when mutual friction becomes important. Using shell model simulations, we propose that for an intermediate regime of temperatures, such that the density of normal and superfluid components are comparable to each other, there exists a range of scales in which the effective exponents indicate stronger intermittency. We offer a bridge relation between these effective and the classical scaling exponents. Since this effect occurs at accessible temperatures and Reynolds numbers, we propose that experiments should be conducted to further assess the validity and implications of this prediction.