Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 72
Primeira ... 1234 ... Última
Imagem não selecionada

Imprime registro no formato completo
A 3D study of the bubble sweep-down phenomenon around a 1/30 scale ship model ArchiMer
Mallat, Bachar; Germain, Gregory; Billard, Jean-yves; Gaurier, Benoit.
The bubble sweep-down phenomenon around oceanographic research vessels generates acoustic disturbances. A specific experimental protocol in a wave and current circulating tank is used to study this phenomenon around a 1/30 scale ship model in a configuration with current, waves and ship motions. 3D visualizations of the bubble clouds and Stereo-PIV (Particle Image Velocimetry) measurements results, both obtained in the bow vicinity of the ship model, are presented in this paper. The behaviour of the breaking wave with bubble generation is studied and the spatial evolution of the bubble clouds is investigated. It is demonstrated that the bubble cloud generation is mainly conditioned by the ascending vertical velocity of the flow near the bow. It is observed...
Tipo: Text Palavras-chave: Bubble sweep-down; Breaking wave; Bow wave; Fluid-structure interaction; Flume tank.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00453/56423/58534.pdf
Imagem não selecionada

Imprime registro no formato completo
A self-regularising DVM–PSE method for the modelling of diffusion in particle methods ArchiMer
Mycek, Paul; Pinon, Gregory; Germain, Gregory; Rivoalen, Elie.
The modelling of diffusive terms in particle methods is a delicate matter and several models have been proposed in the literature. The Diffusion Velocity Method (DVM) consists in rewriting these terms in an advective way, thus defining a so-called diffusion velocity. In addition to the actual velocity, it is used to compute the particles displacement. On the other hand, the well-known and commonly used Particle Strength Exchange method (PSE) uses an approximation of the Laplacian operator in order to model diffusion. This approximation is based on an exchange of particles strength. Although DVM is particularly well suited to particle methods since it preserves their Lagrangian aspect, its major drawback stems in the fact that it suffers from severe...
Tipo: Text Palavras-chave: Particle method; Diffusion; DVM; PSE.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00159/27006/25254.pdf
Imagem não selecionada

Imprime registro no formato completo
A Synthetic turbulence model for numerical simulation of marine current turbine ArchiMer
Carlier, Clement; Pinon, Gregory; Gaurier, Benoit; Germain, Gregory; Rivoalen, Elie.
The ambient turbulence intensity is a key factor in the study of marine current turbines. Indeed recent studies have shown that ambient turbulence intensity highly modifies the behavior of horizontal axis marine current turbines. Consequently numerical simulations have to represent the ambient turbulence or at least its effects on the performance and wake of the turbines. This paper presents the latest numerical developments carried out at LOMC in collaboration with IFREMER in order to take into account the effects of ambient turbulence.
Tipo: Text
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00252/36293/34822.pdf
Imagem não selecionada

Imprime registro no formato completo
Account of ambient turbulence for turbine wakes using a Synthetic-Eddy-Method ArchiMer
Pinon, Gregory; Carlier, Clement; Fur, Arnaud; Gaurier, Benoit; Germain, Gregory; Riyoalen, Elie.
The present paper aims at describing the use of a Synthetic-Eddy-Method (SEM), initially proposed by Jarrin et al. [12], in the 3D Lagrangian Vortex method framework. The SEM method is used here in order to generate a far-field incoming flow with a prescribed ambient turbulence intensity. However, for the account of the diffusive term in the Navier-Stokes equations, a classical Particle Strength Exchange model with a LES eddy viscosity is used. Firstly, the general characteristics of the Synthetic-Eddy-Method will be presented together with its integration in the framework of the developed 3D unsteady Lagrangian Vortex software [27]. The capability of the ambient turbulence model to reproduce a perturbed flow that verifies any turbulence intensity I∞ and...
Tipo: Text
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00389/50002/50587.pdf
Imagem não selecionada

Imprime registro no formato completo
An experimental comparison of three Towed Underwater Video Systems using species metrics, benthic impact and performance ArchiMer
Sheehan, Emma V.; Vaz, Sandrine; Pettifer, Erin; Foster, Nicola L.; Nancollas, Sarah J.; Cousens, Sophie; Holmes, Luke; Facq, Jean-valery; Germain, Gregory; Attrill, Martin J..
Managing ecological systems, which operate over large spatial scales, is inherently difficult and often requires sourcing data from different countries and organizations. The assumption might be made that data collected using similar methodologies are comparable, but this is rarely tested. Here, benthic video data recorded using different towed underwater video systems (TUVSs) were experimentally compared. Three technically different TUVSs were compared on different seabed types (rocky, mixed ground and sandy) in Kingmere Marine Conservation Zone, off the south coast of England. For each TUVS, species metrics (forward facing camera), seabed impact (backward facing camera) and operational performance (strengths and limitations of equipment and video...
Tipo: Text Palavras-chave: Environmental management; Marine protected area; Meta-analyses; Sampling impact; Towed video; Underwater imagery.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00319/42984/42659.pdf
Imagem não selecionada

Imprime registro no formato completo
Analyse par POD de l'écoulement turbulent autour d'une structure souple, poreuse et en mouvement libre ArchiMer
Druault, Philippe; Bouhoubeiny, Elkhadim; Germain, Gregory.
Tipo: Text
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00141/25201/23309.pdf
Imagem não selecionada

Imprime registro no formato completo
Analysis of hydrodynamics of a moving trawl codend and its fluttering motions in flume tank ArchiMer
Druault, Philippe; Germain, Gregory.
The coupled dynamics of the codend fluttering motion and its hydrodynamics behavior are investigated based on PIV measurements carried out around a 1/10 scaled model codend. The mean wake flow characteristics are firstly analyzed demonstrating the great effect of the codend motion. The differences in flow contour between fluttering motion and no-fluttering codend are highlighted by analyzing the classical mean characteristics of a body wake flow. In presence of fluttering motion, the classical results are recovered only if one considers the vertical extent of the codends oscillations as a reference length scale. Secondly, the frequency content of codend oscillations is analyzed and it is linked to the physical mechanisms. It is observed that the motion of...
Tipo: Text Palavras-chave: PIV measurements; Fishing net structure; Wake hydrodynamics; Fluttering structure.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00344/45503/45055.pdf
Imagem não selecionada

Imprime registro no formato completo
Analytical linear modelization of a buckled undulating membrane tidal energy converter ArchiMer
Trasch, Martin; Deporte, Astrid; Delacroix, Sylvain; Germain, Gregory; Drevet, Jean-baptiste.
This paper presents an analytical linear model developed to study the behaviour of a buckled membrane tidal energy converter. The Euler beam theory and the elongated body theory are used for the fluid structure interaction formulation. The effect of electromechanical converters used to convert the undulating motion into electrical energy is reproduced by adding a term equivalent to viscous material damping. The influence of compression force, flaps and hanging conditions is studied, as well as the effects of simulated power take-off through internal damping. The system's behaviour is characterized by undulating mode, critical flow velocity, motion frequency and amplitude. The model shows good agreement in terms of frequency and satisfactory results for the...
Tipo: Text Palavras-chave: Marine renewable energy; Tidal energy converter; Power take-off; Fluid-structure interaction; Slender body theory.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00445/55631/57277.pdf
Imagem não selecionada

Imprime registro no formato completo
Automatic dynamic mask extraction for PIV images containing an unsteady interface, bubbles, and a moving structure ArchiMer
Dussol, David; Druault, Philippe; Mallat, Bachar; Delacroix, Sylvain; Germain, Gregory.
When performing Particle Image Velocimetry (PIV) measurements in complex fluid flows with moving interfaces and a two-phase flow, it is necessary to develop a mask to remove non-physical measurements. This is the case when studying, for example, the complex bubble sweep-down phenomenon observed in oceanographic research vessels. Indeed, in such a configuration, the presence of an unsteady free surface, of a solid–liquid interface and of bubbles in the PIV frame, leads to generate numerous laser reflections and therefore spurious velocity vectors. In this note, an image masking process is developed to successively identify the boundaries of the ship and the free surface interface. As the presence of the solid hull surface induces laser reflections, the hull...
Tipo: Text Palavras-chave: Particle image velocimetry; Unsteady free interface; Edge detection method; Morphological analysis.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00327/43778/43335.pdf
Imagem não selecionada

Imprime registro no formato completo
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
Imagem não selecionada

Imprime registro no formato completo
Bubble sweep-down occurrence characterization on Research Vessels ArchiMer
Delacroix, Sylvain; Germain, Gregory; Berger, Laurent; Billard, Jean-yves.
Bubble sweep-down on oceanographic vessels generates acoustic perturbations. We propose in this work to characterize the sub-surface bubbles occurrence conditions from acoustic data analysis acquired during surveys in relatively shallow water with the IFREMER research vessels Thalassa and Pourquoi Pas?. The methodology of data analysis used in this work allows us to characterize the sailing conditions influence on bubble sweep-down occurrence. The correlation between sailing conditions and acoustic perturbations tends to demonstrate that the presence of bubbles under the hull is clearly related to the wind speed and natural aeration, and that surface bubbles are advected differently in the water column by the two vessels
Tipo: Text Palavras-chave: Bubble sweep-down; Acoustic perturbation; Ship motion.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00294/40557/39632.pdf
Imagem não selecionada

Imprime registro no formato completo
Caractérisation d'effets de sillages rencontrés en milieu offshore ArchiMer
Gaurier, Benoit; Germain, Gregory; Le Boulluec, Marc; Giry, Eric; Fontaine, E..
The interactions between several cylinders placed in close proximity are the subject of many studies, because of the strong repeated loads that they create on these structures. For flexible or mobile structures, the wake effects can produce large amplitudes motions. These displacements can be higher than those considered during the lock-in of a single cylinder, to reach several diameters. Depending the initial spacing, they lead sometimes to clashes with potentially high intensity, between the cylinders. To better understand these phenomena, an experimental study was carried out, bearing on the interaction between two models of tensioning buoy supporting hybrid risers. After checking that the models used were able to correctly reproduce the movements...
Tipo: Text
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00023/13439/10447.pdf
Imagem não selecionada

Imprime registro no formato completo
Caractérisation expérimentale du sillage généré par une hydrolienne - Influence du taux de turbulence ambiant ArchiMer
Maganga, Fabrice; Germain, Gregory; Facq, Jean-valery; Gaurier, Benoit; Rivoalen, Elie; Pinon, Grégory.
Le fonctionnement d’une hydrolienne est régi par les caractéristiques de l’écoulement incident. Cet article présente les résultats d’une étude expérimentale visant à déterminer les effets du taux de turbulence de l’écoulement ambiant sur le fonctionnement d’une hydrolienne et le sillage généré. Les essais expérimentaux ont été réalisés dans la veine hydrodynamique à surface libre de l’Ifremer, dont on peut faire varier le taux de turbulence de l’écoulement de 5 à 25%. Le prototype utilisé est une turbine tri-pales à axe horizontal de 0,7 m de diamètre (échelle 1/30). Des cartes de vitesses moyennes, de taux de turbulence, mais également d’énergie cinétique turbulente et de contrainte de cisaillement ont été obtenus à partir de mesures par vélocimétrie...
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00022/13355/10386.pdf
Imagem não selecionada

Imprime registro no formato completo
Caractérisation expérimentale et numérique d’hydroliennes : études de deux hydroliennes en interaction ArchiMer
Carlier, Clement; Pinon, Gregory; Mycek, Paul; Gaurier, Benoit; Germain, Gregory; Rivoalen, Elie.
The development of marine current turbines arrays still needs nowadays many studies among which we can find the study of interactions between devices. In order to highlight these interactions effects, experiments were carried out in the IFREMER’s (Boulogne-sur-Mer) flume tank. Those experiments used 3-bladed horizontal axis marine current turbines prototypes, regulated in rotation speed. To complete these experiments, a three-dimensional numerical tool is developed at the LOMC (Université du Havre) to simulate one or more turbines in a free upstream current. We present hereafter the numerical and experimental results obtained in the scope of the study of elementary interaction between two turbines axially aligned with the upstream current.
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00247/35806/34320.pdf
Imagem não selecionada

Imprime registro no formato completo
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
Imagem não selecionada

Imprime registro no formato completo
Compte rendu final d’exécution de l’opération dans le cadre du projet HydroPêche ArchiMer
Germain, Gregory; Priour, Daniel; Vincent, Benoit; Billard, Jean-yves; Druault, Philippe; Bouhoubeiny, Elkhadim; Alexandrini, Bertrand; Le Touze, David; Khaled, Ramez; Mnassri, Ilyes.
Le comportement hydrodynamique des structures poreuses utilisées pour la pêche (chaluts, nasses, cages, seines) est aujourd’hui encore mal connu. Les chaluts étant responsables de la plus grosse part de la consommation de fuel en action de pêche, ce projet a pour objectif de développer un outil de conception de chalut permettant de réduire au maximum la traînée de l’engin.L’outil ainsi développé devrait permettre d’obtenir un gain de l’ordre de 20% sur la traînée d’un chalut, tout en conservant une efficacité en pêche comparable. Les développements réalisés pourront également être étendus pour étudier les différents types de structures poreuses utilisées pour la pêche et mieux appréhender le développement de dispositifs de sélectivité.
Tipo: Text
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00116/22716/20683.pdf
Imagem não selecionada

Imprime registro no formato completo
Couche limite et sillage rencontrés sur un chalut de fond ArchiMer
Bouhoubeiny, Elkhadim; Germain, Gregory; Druault, Philippe; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas.
Flow field measurements around a bottom trawl are conducted using Time Resolved PIV method. Using the Proper Orthogonal Decomposition (POD) for such investigation, it is demonstrated the effectiveness of this procedure to characterize the boundary layer above the horizontal part of this porous structure and to extract the large scale spatial flow structure and their associated frequencies in the wake of the cod-end.
Tipo: Text
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00037/14815/12127.pdf
Imagem não selecionada

Imprime registro no formato completo
Développements numériques pour la modélisation du comportement et du sillage d'hydroliennes ArchiMer
Mycek, Paul; Pinon, Gregory; Germain, Gregory; Rivoalen, Elie; Gaurier, Benoit.
Developments of new marine current turbines farm are subject to a better understanding of interactions effects between the turbines. Experimental trials have been realised in the wave and current flume of IFREMER Boulogne-sur-Mer, on a three bladed horizontal axis marine current turbine in order to characterise the elementary interaction between two turbines aligned with the current. At the same time, a three-dimensional numerical software has been developed in order to model the flow behind a marine current turbine. The software is based on a Lagrangian Vortex Method. It enables to evaluate the forces and moments onto the rotor as well as the flow fields around the turbine. Most of the previous numerical studies regarding interaction between devices only...
Tipo: Text
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00141/25200/23360.pdf
Imagem não selecionada

Imprime registro no formato completo
Effet des concrétions marines sur le comportement hydrodynamique de structures circulaires ArchiMer
Gaurier, Benoit; Germain, Gregory; Facq, Jean-valery; Baudet, L.; Birades, M.; Schoefs, F..
The presence of marine growth on underwater parts of jackets significantly increases diameter and roughness of tubular members of these structures. This paper escribes an experimental study carried out in the circulating tank of Boulogne-sur-mer which aim to quantify the hydrodynamical drag and added-mass coefficients of a circular cylinder encrusted with rigid and large-size biofouling, such as coral. Two different kinds of roughness are studied and compared to a reference cylinder. These coefficients are obtained from trials with current only, with imposed motions or with a combination of imposed motions and current. Results show that these coefficients are from 1.5 to 4 times higher 1 than those obtained for the reference cylinder. Nevertheless,...
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00247/35821/34349.pdf
Imagem não selecionada

Imprime registro no formato completo
Etude d’une hydrolienne à membrane ondulante à convertisseurs linéaires ArchiMer
Deporte, Astrid; Germain, Gregory; Trasch, M.; Davies, Peter; Drevet, J. B..
Tidal energy converters are mostly marine turbines. They have many disavantages in sea where the environment is very inhospitable. We study a new system based on undulating membrane. Pressure deforms the device periodically, we observe a wave propagating along the length. Electromagnetic converters are distributed over the length of the membrane and act like dampers. In this paper, we present numerical and experimental developments carried out to study the system’s behavior.
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00246/35765/34278.pdf
Registros recuperados: 72
Primeira ... 1234 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional