Vorticity Locking and Pressure Dynamics in Finite-Temperature Superfluid Turbulence

TL;DR

This study uses numerical simulations to explore vorticity locking, pressure dynamics, and turbulence characteristics in finite-temperature superfluid helium, revealing temperature-dependent behaviors and verifying theoretical pressure spectrum predictions.

Contribution

It demonstrates how vorticity locking varies with temperature and influences turbulence and pressure spectra in superfluid helium, using novel numerical approaches.

Findings

Vorticity locking increases with temperature.

Superfluid flow becomes more influenced by normal fluid characteristics.

Pressure spectrum follows the $P_k\propto k^{-7/3}$ scaling at certain conditions.

Abstract

We present a numerical study of finite-temperature superfluid turbulence using the vortex filament model for superfluid helium. We examine the phenomenon of vorticity locking between the normal and superfluid components across a wide range of temperatures, using two different structures of external normal fluid drive. We show that vorticity locking increases with temperature leading to the superfluid flow being more influenced by the characteristics of the normal fluid. This also results in stronger superfluid polarization and turbulent intermittency. We also examine how these properties influence the pressure field and attempt to verify a long-standing $P_k\propto k^{-7/3}$ theoretical quantum signature within the spatial pressure spectrum.