Réflexions et réfractions non-linéaires d'ondes de gravité internes

Abstract : Internal wave studies are crucial to the understanding of deep-ocean mixing. In this thesis, we first describe a 2D direct numerical simulation of a wave attractor and validate it against pre-existing experimental data. We then propose a model for the thickness of the attractor along the direction of propagation of energy. We eventually study nonlinear effects induced by the attractor. In a second part, we describe an experimental study of the reflection of plane waves on a sloping wall. Unexpectedly, resonances between different wave harmonics are not observed. However, a horizontal mean flow is generated and the wave characteristics are curved, due to the Doppler effect. 70 to 80% of the incident energy flux is dissipated and transferred to the mean flow, the latter being seemingly generated by wave dissipation. In a third part, we perform a numerical study of the generation of internal solitary waves by an impinging wave beam. We first present direct numerical simulations of this process and show that different solitary wave modes can be excited. Criteria for the selection of a particular mode are put forward, the first one being in terms of phase speeds and the second one based on geometrical arguments. Results are compared with the configuration of the Bay of Biscay in summer. We show that a beam impinging on a thermocline initially at rest can not generate solitary waves which features agree with oceanic observations. This can be corrected by taking into account the background flow around the thermocline as found in the Bay of Biscay and independent of the internal wave beam.
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Contributor : Nicolas Grisouard <>
Submitted on : Sunday, November 28, 2010 - 11:54:45 AM
Last modification on : Thursday, January 3, 2019 - 4:30:08 PM
Long-term archiving on : Friday, December 2, 2016 - 4:37:54 PM

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Nicolas Grisouard. Réflexions et réfractions non-linéaires d'ondes de gravité internes. Physique [physics]. Université de Grenoble, 2010. Français. ⟨tel-00540608⟩

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