|Copyright||2017 American Physical Society|
|Author(s)||Aubourg Quentin1, Campagne Antoine1, Peureux Charles2, Ardhuin Fabrice3, Sommeria Joel1, Viboud Samuel1, Mordant Nicolas1|
|Affiliation(s)||1 : Univ Grenoble Alpes, CNRS, Lab Ecoulements Geophys & Ind, F-38000 Grenoble, France.
2 : Univ Brest, CNRS, IFREMER, Lab Oceanog Phys & Spatiale,IRD, F-29200 Plouzane, France.
|Source||Physical Review Fluids (2469-990X) (Amer Physical Soc), 2017-11 , Vol. 2 , N. 11 , P. 114802 (1-19)|
Weak-turbulence theory is a statistical framework to describe a large ensemble of nonlinearly interacting waves. The archetypal example of such system is the ocean surface that is made of interacting surface gravity waves. Here we describe a laboratory experiment dedicated to probe the statistical properties of turbulent gravity waves. We set up an isotropic state of interacting gravity waves in the Coriolis facility (13-m-diam circular wave tank) by exciting waves at 1 Hz by wedge wave makers. We implement a stereoscopic technique to obtain a measurement of the surface elevation that is resolved in both space and time. Fourier analysis shows that the laboratory spectra are systematically steeper than the theoretical predictions and the field observations in the Black Sea by Leckler et al. [F. Leckler et al., J. Phys. Oceanogr. 45, 2484 (2015)]. We identify a strong impact of surface dissipation on the scaling of the Fourier spectrum at the scales that are accessible in the experiments. We use bicoherence and tricoherence statistical tools in frequency and/or wave-vector space to identify the active nonlinear coupling. These analyses are also performed on the field data by Leckler et al. for comparison with the laboratory data. Three-wave coupling is characterized by and shown to involve mostly quasiresonances of waves with second- or higher-order harmonics. Four-wave coupling is not observed in the laboratory but is evidenced in the field data. We discuss temporal scale separation to explain our observations.
Aubourg Quentin, Campagne Antoine, Peureux Charles, Ardhuin Fabrice, Sommeria Joel, Viboud Samuel, Mordant Nicolas (2017). Three-wave and four-wave interactions in gravity wave turbulence. Physical Review Fluids, 2(11), 114802 (1-19). Publisher's official version : http://doi.org/10.1103/PhysRevFluids.2.114802 , Open Access version : http://archimer.ifremer.fr/doc/00410/52141/