12,000

We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK

93%

93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Acoustic Turbulence in Superfluid 4He.
View graph of relations

« Back

Acoustic Turbulence in Superfluid 4He.

Research output: Contribution to journalJournal article

Published

Journal publication date09/2009
JournalJournal of Low Temperature Physics
Journal number3-6
Volume156
Number of pages21
Pages95-115
Original languageEnglish

Abstract

Recent work on nonlinear second sound wave propagation and acoustic turbulence in superfluid 4He is reviewed. Observations of direct and inverse turbulent energy cascades are described. The direct cascade arises due to the huge nonlinear dependence of the second sound wave velocity on its amplitude. The flux of energy injected at the driving frequency is transformed via successively higher harmonics until it is eventually attenuated by viscous dissipation at the short wavelength edge of the spectrum. The onset of the inverse cascade occurs above a critical driving energy density, and it is accompanied by giant waves that constitute an acoustic analogue of the rogue waves that occasionally appear on the surface of the ocean. The theory of the phenomena is outlined and shown to be in good agreement with the experiments.