Experimental study of parametric subharmonic instability for internal waves

Abstract

Internal waves are believed to be of primary importance as they affect ocean mixing and energy transport. Several processes can lead to the breaking of internal waves and they usually involve non linear interactions between waves. In this work, we study experimentally the parametric subharmonic instability (PSI), which provides an efficient mechanism to transfer energy from large to smaller scales. It corresponds to the destabilization of a primary plane wave and the spontaneous emission of two secondary waves, of lower frequencies and different wave vectors. Using a time-frequency analysis, we observe the time evolution of the secondary waves, thus measuring the growth rate of the instability. In addition, a Hilbert transform method allows the measurement of the different wave vectors. We compare these measurements with theoretical predictions, and study the dependence of the instability with primary wave frequency and amplitude, revealing a possible effect of the confinement due to the finite size of the beam, on the selection of the unstable mode.

References in corpus (5)

• A novel internal waves generator
• Experimental evidence of a triadic resonance of plane inertial waves in a rotating fluid
• New wave generation
• Resonant Triad Instability in Stratified Fluids
• A laboratory study of low-mode internal tide scattering by finite-amplitude topography

Cited by in corpus (25)

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• Finite-size effects in parametric subharmonic instability
• Internal wave attractors: different scenarios of instability
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• Linear and nonlinear regimes of an inertial wave attractor
• Internal Wave Attractors in 3D Geometries : trapping by oblique reflection
• Vortex cluster arising from an axisymmetric inertial wave attractor
• Scale effects in internal wave attractors
• Parametric instability and wave turbulence driven by tidal excitation of internal waves
• A study of turbulence and interacting inertial modes in a differentially-rotating spherical shell experiment
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• Three-dimensionality of the triadic resonance instability of a plane inertial wave
• Mixing and formation of layers by internal wave forcing
• Nonlinear internal wave penetration via parametric subharmonic instability
• The long view of triadic resonance instability in finite-width internal gravity wave beams
• Variational Mode Decomposition for estimating critical reflected internal wave in stratified fluid
• Synthetic Schlieren -- application to the visualization and characterization of air convection
• Evidence of experimental three-wave resonant interactions between two dispersion branches
• The stability of propagating plane inertial waves in rotating fluids