Internal waves and mean flow in the presence of topography
Internal waves play an important role in many processes in oceans. The interaction be-tween internal waves and ocean topography has been an active field of research for long. Yetthere are many questions remaining on the topic. In this thesis, two main processes are ex-amined namely, the reflection o...
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| Other Authors: | , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
HAL CCSD
2018
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| Subjects: | |
| Online Access: | https://tel.archives-ouvertes.fr/tel-01799047 https://tel.archives-ouvertes.fr/tel-01799047/document https://tel.archives-ouvertes.fr/tel-01799047/file/RAJA_2018_archivage.pdf |
| Summary: | Internal waves play an important role in many processes in oceans. The interaction be-tween internal waves and ocean topography has been an active field of research for long. Yetthere are many questions remaining on the topic. In this thesis, two main processes are ex-amined namely, the reflection of internal wave beams on a slope, and generation of lee wavesover a three-dimensional obstacle, using laboratory experiments and numerical simulations.The nonlinear reflection of an internal wave beam on a uniform slope is studied using two-dimensional inviscid theory and numerical simulations. The resonant triadic interactionsamong the incident, reflected and second harmonic wave beams are investigated developingon existing theory and verifying them with results for numerical simulations.In the case of reflection of three-dimensional internal wave beams, a strong mean horizon-tal flow is found to be induced by the wave beam, which perturbs the wave field and weakensthe second harmonics. The generation of this wave-induced mean flow is examined usingresults from experiments and three-dimensional numerical simulations. Furthermore, theeffects of background rotation on the wave induced mean flow are also studied using numer-ical simulations.The Antarctic Circumpolar Current is considered as one of the main sources of mixing inoceans. Laboratory modelling of the Antarctic Circumpolar Current was done in the Coriolisplatform at LEGI to study the topography induced drag on the current. The experiment andits results are also presented. Les ondes internes jouent un rôle important dans de nombreux processus dans les océans.L’interaction entre les vagues internes et la topographie océanique a longtemps été un champ de recherche actif. Pourtant, il reste beaucoup de questions sur le sujet. Dans cette thèse, deux processus principaux sont examinés, à savoir la réflexion de faisceaux d’ondes internes sur une pente, et la génération d’ondes sous le vent sur un obstacle tridimensionnel, en utilisant des expériences de laboratoire ... |
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