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Attracteurs d’ondes internes de gravité : des résonances en cascade : une approche expérimentale des régimes linéaire et non linéaire

Abstract : Internal waves are very important to atmospheric and oceanic dynamics. Among others, they might explain the irreversible mixing of the oceans. In particular geometries, these waves can focus on limit cycles called attractors. Firstly, we investigate the energy budget of these attractor by measuring the different dissipative terms and the injected power coming from the waves source. If this power is sufficient, the attractor destibilise throught triadic instabilities. We quantify how much these secondary are important to the global dissipation rate.The measurement of injected power in the linear regime has shown that it is bigger for the attractors. This resonance, which had been observed under a monochromatic excitation, is here study by analysing the response of the system to an impulse. A theoretical development is proposed to compare quantitatively these two methods. Finally, we study the non linear regime of attractors, which present some complex spatial and temporal spectrum. We caracterise this non linear regime and show that two very different non linear beahviors exist. We bring up some explanation to these behaviors
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Géraldine Davis. Attracteurs d’ondes internes de gravité : des résonances en cascade : une approche expérimentale des régimes linéaire et non linéaire. Physique [physics]. Université de Lyon, 2019. Français. ⟨NNT : 2019LYSE1147⟩. ⟨tel-02463462⟩

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