Turbulent velocity spectra in superfluid flows

TL;DR

This study measures velocity spectra in superfluid and classical helium flows, finding that turbulence statistics below the superfluid transition resemble those of classical turbulence, across various flow conditions.

Contribution

It provides experimental velocity spectra data in superfluid helium flows across different regimes, showing no significant difference from classical turbulence statistics.

Findings

Turbulence spectra in superfluid helium match classical turbulence.

Velocity spectra cover up to two decades of the inertial range.

Superfluid turbulence statistics are similar to classical turbulence.

Abstract

We present velocity spectra measured in three cryogenic liquid 4He steady flows: grid and wake flows in a pressurized wind tunnel capable of achieving mean velocities up to 5 m/s at temperatures above and below the superfluid transition, down to 1.7 K, and a "chunk" turbulence flow at 1.55 K, capable of sustaining mean superfluid velocities up to 1.3 m/s. Depending on the flows, the stagnation pressure probes used for anemometry are resolving from one to two decades of the inertial regime of the turbulent cascade. We do not find any evidence that the second order statistics of turbulence below the superfluid transition differ from the ones of classical turbulence, above the transition.