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Mini-séminaire du LHEEA 16/11/2017 : "Reconstruction et prédiction en temps réel de champs de vagues par télédétection optique", Nicolas Desmars

Le Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique de Centrale Nantes (LHEEA) organise des mini-séminaires tous les jeudis midi. Rendez-vous en salle de télé-enseignement au bâtiment D les jeudis à 13h45. Allez-y, c'est ouvert à tous !

Le 16 novembre 2017 de 13:45 à 14:30

Le 16 novembre 2017 de 13:45 à 14:30

Le 16 novembre 2017 de 13:45 à 14:30

Le 16 novembre 2017 de 13:45 à 14:30

Cette semaine :

Nicolas DESMARS (équipe EMO) présentera ses travaux sur "Reconstruction et prédiction en temps réel de champs de vagues par  télédétection optique".

Abstract: "We investigate phase-resolved reconstruction algorithms and models for a deterministic prediction of ocean waves based on optically measured surface elevations. We consider a single sensor (e.g. lidar, stereo-video, etc.) mounted on an offshore structure, measuring free surface elevation at the appropriate incident direction for a given wave field and chosen target area of prediction. If assuming a uniform distribution of measurements over the viewing angles of the sensor, the density of observation points of the free surface geometrically decreases with the distance from the sensor. Additionally, a wave shadowing effect occurs, which becomes more important with small viewing angles (i.e. grazing incidence on the surface). These effects result in observations of surface elevation that are very sparsely distributed. We discuss the characteristics of a data assimilation process, which is able to retrieve fields of deterministic wave properties, such as free surface elevation, based on such a heterogeneously spread dataset. Then, a classical model based on linear wave theory is compared to the choppy wave model. The latter model is based on a Lagrangian formulation of the free surface, capable of modeling wave properties that are shown to be of importance in a proper representation of the free surface and its time evolution. Synthetic datasets from nonlinear High Order Spectral simulations are used as reference oceanic surfaces. Predicted results are analyzed over an area that evolves in time, using the theoretical amount of information assimilated during the reconstruction of the wave field."


Publié le 13 novembre 2017 Mis à jour le 8 juillet 2018