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Registros recuperados: 9
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Boundary layer development and shear stresses measurements around an oyster table ArchiMer
Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Facq, Jean-valery; Cayocca, Florence; Lesueur, Patrick.
Oyster tables are artificial obstacles which are laid over muddy or sandy-muddy floors in intertidal areas. This study aims to show the current modifications related to the presence of the oyster table thanks to LDV measurement in a flume tank. Boundary layer development in different geometric configuration is underlined and suggests some important areas of velocity decrease and sediment transport modification. Shear stresses are also calculated near the bottom and around the table. The total shear stress in the water column exhibits an important increase when the flow passes through the oyster table, hence a flow energy decrease through dissipation. This study helps to understand the reasons for the increased sedimentation observed in some natural sites.
Tipo: Text
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00022/13359/10388.pdf
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Caractérisation numérique et expérimentale des perturbations engendrées par la présence de tables ostréicoles ArchiMer
Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Cayocca, Florence; Lesueur, Patrick.
Sur de nombreux sites ostréicoles, d’importants mouvements sédimentaires modifient les conditions d’exploitation. Les mouvements naturels sont modifiés par la présence des tables à huîtres, les phénomènes en jeu étant de deux ordres : la perturbation des courants de marée et la modification des conditions de houle. Nous présentons dans ce document la méthodologie mise en place pour améliorer la compréhension des perturbations physiques du milieu engendrées par l’implantation de tables ostréicoles et caractériser les modifications de l’écoulement. Les résultats obtenus, tant expérimentaux que numériques, sont présentés et les développements pour une extension du modèle à l’échelle d’un parc ostréicole sont discutés. Des essais expérimentaux réalisés à...
Tipo: Text Palavras-chave: Mesures LDV; Essais expérimentaux; Simulations numériques; Contraintes de cisaillement; Hydrodynamique côtière; Table ostréicole.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12263/9044.pdf
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Comparison between three-dimensional linear and nonlinear tsunami generation models ArchiMer
Kervella, Youen; Dutykh, Denys; Dias, Frédéric.
The modeling of tsunami generation is an essential phase in understanding tsunamis. For tsunamis generated by underwater earthquakes, it involves the modeling of the sea bottom motion as well as the resulting motion of the water above. A comparison between various models for three-dimensional water motion, ranging from linear theory to fully nonlinear theory, is performed. It is found that for most events the linear theory is sufficient. However, in some cases, more-sophisticated theories are needed. Moreover, it is shown that the passive approach in which the seafloor deformation is simply translated to the ocean surface is not always equivalent to the active approach in which the bottom motion is taken into account, even if the deformation is supposed to...
Tipo: Text Palavras-chave: Nonlinear shallow water equations; Potential flow; Water waves; Boundary element method; Finite volume method; Tsunami generation.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2620.pdf
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Experimental and numerical characterization of an oyster farm impact on the flow ArchiMer
Gaurier, Benoit; Germain, Gregory; Kervella, Youen; Davourie, Julia; Cayocca, Florence; Lesueur, Patrick.
Shellfish farming, particularly oyster farms, suffers from strong siltation phenomena which are harmful to the production of shellfish. The lack of knowledge about the impact of an oyster farm on the wave propagation and on the flow remains a significant difficulty for the comprehension of sediment transport processes in coastal zones. These effects are one of the possible sources of sedimentation. The study presented here focuses on describing finely hydrodynamical phenomena (velocity fields, turbulence parameters) around oyster tables. The analysis is based on experimental trials carried out in a flume tank on reduced models of oyster tables. Experiments highlight the flow perturbations in the near field and constitute a database for validation of...
Tipo: Text Palavras-chave: Sediment dynamics; Oyster table; LDV measurement; Computational fluid dynamics; Porosity; Boundary layer.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00043/15421/12974.pdf
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Experimental study of the near-field impact of an oyster table on the flow ArchiMer
Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Facq, Jean-valery; Cayocca, Florence; Lesueur, Patrick.
Oyster farming structures are artificial obstacles which disturb tidal flow and wave propagation. These effects can induce modifications of erosion and sedimentation patterns, turbidity changes, local silting up and can be threatening for the shellfish farming itself. The understanding of the impact of these structures in terms of hydrodynamics and sediment dynamics in the far-field, i.e. at the scale of a bay, is a very challenging task. In order to investigate the far-field impact, it is very important to understand in the first place all the changes which occur at a smaller scale, i.e. at the scale of a single table for a farm consisting of oyster tables made of metallic wire structures on which porous bags of oysters are laid. This work is carried out...
Tipo: Text Palavras-chave: Sediment dynamics; Roughness length; Boundary layer; Particle Image Velocimetry; Laser Doppler Velocimetry; Flume; Oyster table.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/2010/publication-7389.pdf
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Impact des installations ostréicoles sur l’hydrodynamique et la dynamique sédimentaire ArchiMer
Kervella, Youen.
Oyster farm structures represent artificial obstacles which can disturb tidal currents and wave propagation, and thus modify sediment transport patterns. Local deposition may result from these modifications, in proportions that may threaten the oyster farming. The impact of structures on hydrodynamics, waves and currents, is investigated at different spatial scales by means of in-situ measurements, experimental tests and numerical modeling. These different approaches show that in the near-field, tidal currents are modified in terms of intensity and direction but there is no significant impact on the waves. On the other hand, at the scale of the oyster farm, a significant reduction of the current velocities and a large wave height attenuation are recorded....
Tipo: Text Palavras-chave: Tables à huîtres; Envasement; Courants; Vagues; Sédiments; Impact; Oyster tables; Silting up; Currents; Waves; Sediment; Impact.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12262/9043.pdf
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Impact hydrodynamique de la mise en place d’un parc d’hydroliennes en Baie du Mont Saint-Michel ArchiMer
Batifoulier, Francois; Kervella, Youen; Laborde, Renaud; Cuny, Jérôme; Caillaud, Matthieu; Lazure, Pascal; Cayocca, Florence.
Les fortes vitesses rencontrées à l’entrée de la Baie du Mont Saint-Michel font de cet environnement macro-tidal un endroit privilégié, en termes de ressources énergétiques, pour l’implantation d’une ferme d’hydroliennes. Afin d’établir plus précisément son potentiel énergétique et d’évaluer l’impact de l’implantation de telles machines sur son hydrodynamisme, une modélisation hydrodynamique de la Baie du Mont Saint-Michel est mise en oeuvre à l’aide du modèle de circulation régionale MARS3D (LAZURE & DUMAS, 2008) dans sa version tridimensionnelle. La validation hydrodynamique de cette configuration est réalisée à partir de comparaisons à des mesures courantologiques récentes (KERVELLA, 2010). A partir de cette modélisation, une cartographie du...
Tipo: Text Palavras-chave: Modélisation régionale; Hydroliennes; Baie du Mont Saint-Michel; Hydrodynamisme; Potentiel énergétique.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00195/30599/29055.pdf
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Mise en évidence de l’importance de la turbulence ambiante sur les effets d’interaction entre hydroliennes ArchiMer
Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas.
Les futures zones d’implantation des parcs hydroliens en mer sont caractérisées par des courants de forte intensité et des taux de turbulence importants. Cette turbulence de l’écoulement est susceptible d’altérer le comportement des hydroliennes, à la fois en termes de production d’énergie mais aussi de fatigue structurelle. Afin de déterminer l’influence de la turbulence ambiante sur les effets d’interaction entre hydroliennes, des essais expérimentaux ont été effectués dans un bassin à houle et courant, sur des maquettes d’hydroliennes tri-pales à axe horizontal, régulées en vitesse de rotation. Les interactions entre trois hydroliennes placées sur deux rangées (deux hydroliennes sur la rangée amont et une sur la rangée aval, ou inversement) ont été...
Tipo: Text Palavras-chave: Énergie marine; Hydroliennes; Turbulence; Effets d'interaction; Essais expérimentaux..
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00212/32342/30782.pdf
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Utilisation d’un altimètre (ALTUS) destiné à la quantification des dépôt/érosion en domaine littoral pour l’étude des corrélations avec les caractéristiques de vagues et les interfaces de dépôt ArchiMer
Bassoullet, Philippe; Verney, Romaric; Kervella, Youen; Kervella, Stephane; Jestin, Herve; Voineson, Guillaume.
Quantitative evaluation of erosion/deposition events of surficial sediments is crucial to understand the processes and establish sedimentary budgets in coastal areas The ALTUS system was designed for more than a decade, to meet this objective The possibilities offered by this altimeter (short-term or several months measurements) are particularly fitted for validation of sedimentary transport numerical models The recent integration of a large capacity memory card has allowed to optimize the system Indeed it is well established that wave activity is one of the key parameters for the erosion and hence govern sediment transport in intertidal/shallow water areas The ALTUS system in addition to bottom level variation recordings allows access to wave...
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00019/13036/10170.pdf
Registros recuperados: 9
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