The Generation of Turbulence by Oscillating Structures in Superfluid Helium at Very Low Temperatures

TL;DR

This paper investigates how oscillating structures generate quantum turbulence in superfluid helium at very low temperatures, comparing experimental results with classical analogues and simulations to understand differing behaviors in helium-4 and helium-3.

Contribution

It provides a comparative analysis of turbulence generation in superfluid helium and classical fluids, highlighting differences between helium-4 and helium-3 at ultra-low temperatures.

Findings

In helium-4, turbulence behavior resembles classical fluids with minor size effects.

In helium-3, turbulence differs significantly, likely due to rapid vortex nucleation.

Critical velocities vary markedly between helium-4 and helium-3.

Abstract

The paper is concerned with the interpretation of many experiments that have been reported recently on the production of quantum turbulence by oscillating spheres, wires and grids in both 4He and 3He-B at temperatures so low that there is a negligible fraction of normal fluid. The experimental results are compared with those obtained in analogous experiments with classical fluids and with preliminary simulations of the quantum turbulence. Particular attention is paid to observed values of drag coefficients and to the very different critical velocities observed in 4He and 3He. It is tentatively concluded that in the case of 4He behaviour may well be similar to that observed in the classical analogues, with relatively small changes when the characteristic size of the oscillating structure is not large compared with the quantized vortex spacing, but that in the case of 3He behaviour is very different and due perhaps to very rapid intrinsic nucleation of the quantized vortices.