Kelvin-wave turbulence in superfluids

TL;DR

This paper investigates the energy spectrum of Kelvin waves in superfluid turbulence, providing analytical and numerical evidence supporting a specific spectrum and revealing intermittent behaviors at weak forcing.

Contribution

It analytically confirms the existence and regularity of a proposed Kelvin wave spectrum and demonstrates numerical agreement with non-local theories, clarifying energy dissipation mechanisms.

Findings

Analytical proof of the spectrum's existence, uniqueness, and regularity.

Numerical results align with non-local Kelvin wave theories.

Observation of intermittent spectrum behavior at weak forcing.

Abstract

We study the statistical and dynamical behavior of turbulent Kelvin waves propagating on quantized vortices in superfluids, and address the controversy concerning the energy spectrum that is associated with these excitations. Finding the correct energy spectrum is important because Kelvin waves play a major role in the dissipation of energy in superfluid turbulence at near-zero temperatures. In this paper, we show analytically that the solution proposed in Ref. \cite{10LN} enjoys existence, uniqueness and regularity of the pre-factor. Furthermore, we present numerical results of the dynamical equation that describes to leading order the non-local regime of the Kelvin wave dynamics. We compare our findings with the analytical results from the proposed local and non-local theories for Kelvin wave dynamics and show an agreement with the non-local predictions. Accordingly, the spectrum proposed in Ref. \cite{10LN} should be used in future theories of quantum turbulence. Finally, for weaker wave forcing we observe an intermittent behavior of the wave spectrum with a fluctuating dissipative scale, which we interpreted as a finite-size effect characteristic to mesoscopic wave turbulence.