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Nonlinear second sound waves in superfluid helium: instabilities, turbulence and rogue waves

Research output: Contribution to journalJournal article

Published

Article number1250242
Journal publication date10/2012
JournalInternational Journal of Bifurcation and Chaos
Journal number10
Volume22
Number of pages20
Pages-
Original languageEnglish

Abstract

Recent work on nonlinear second sound wave propagation and acoustic turbulence in superfluid He-4 is reviewed. Observations of direct and inverse turbulent energy cascades are described. The direct cascade arises due to the strong 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.