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Registros recuperados: 17
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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: https://archimer.ifremer.fr/doc/00319/42984/42659.pdf
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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 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...
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00022/13355/10386.pdf
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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
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Deployment of new observing systems within the JERICO-RI ArchiMer
Puillat, Ingrid; Carlier, Antoine; Facq, Jean-valery; Rubio, Anna; Lazure, Pascal; Delauney, Laurent; Petihakis, George; Karlson, Bengt; Artigas, Felipe; Farcy, Patrick.
A key message of the JERICO-RI consortium (2014): “The complexity of the coastal ocean cannot be well understood if interconnection between physics, biogeochemistry and biology is not guaranteed. Such integration requires new technological developments allowing continuous monitoring of a larger set of parameters”. In agreement with this consideration, several new observing systems are developed, tested and deployed in the framework of the JERICO-NEXT H2020 project, amongst which a few of them will be presented as well as some preliminary results after the first deployments. Focus will be given on coastal transports and hydrology and on benthic biodiversity. In the first case, we will present a low cost 2D moored system dedicated to acquire vertical...
Tipo: Text Palavras-chave: JERICO; JERICO-NEXT; Coastal; Ocean Observing System (OOS); Harmonization.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00437/54866/56359.pdf
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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
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Etude d’outils d’évaluation de la contamination ChimiqUe dans les eaux de la ManchE - ECUME ArchiMer
Menet-nedelec, Florence; Halm-lemeille, Marie-pierre; Maheux, Frank; Pierre-duplessix, Olivier; Simon, Benjamin; Gonzalez, Jean-louis; Repecaud, Michel; Facq, Jean-valery.
L’étude ECUME était une opération destinée à tester localement dans les eaux côtières du littoral normand, des outils développés nationalement lors de nombreux travaux, et pressentis pour être utilisés lors des prochaines campagnes d’évaluation de la qualité chimique des masses d’eau littorales pour la DCE.  Ceci afin de déterminer la méthode la plus adaptée et opérationnelle de les déployer, et comparer leurs résultats entre eux et par rapport aux connaissances actuelles des niveaux de contamination. Trois sites ont été choisis : Chausey, baie des Veys et estuaire de Seine. Les résultats des analyses chimiques dans l’eau de mer grâce aux DGT, POCIS, SBSE, et dans les moules ont permis de confirmer le contraste du niveau de contamination en éléments traces...
Tipo: Text Palavras-chave: Contamination chimique; Chausey; Baie des Veys; Estuaire de Seine; DGT; POCIS; SBSE; Biomarqueurs; Stabilité lysosomale; Micronoyaux; Activité catalase; Métaux; Pesticides; Substances pharmaceutiques; HAP; PCB; Phtalates; Alkylphénols.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00434/54582/55966.pdf
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Etude expérimentale du phénomène d’entraînement de bulles à l’étrave des navires scientifiques ArchiMer
Delacroix, Sylvain; Germain, Gregory; Billard, Jean-yves; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas.
The bubble sweep-down phenomenon around the hull of scientific vessels leads to a disruption of the acoustic waves emitted by the sonars, and a loss of productivity during the acoustic surveys. Numerical or experimental tools used to study this phenomenon still have limitations, mainly due to scale effects on bubbles generation. An innovative method in a circulating tank, using numerical simulations and a motions generator, has been developed. Two mechanisms of air entrainment have been described, as well as the influence of waves characteristics and turbulence on bubbles generation.
Tipo: Text
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00247/35807/34321.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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Experimental study of the wake of a wide wall-mounted obstacle on the behaviour of a marine current turbine ArchiMer
Gaurier, Benoit; Ikhennicheu, Maria; Druault, Philippe; Germain, Gregory; Facq, Jean-valery; Pinon, Grégory.
In high flow velocity areas like those suitable for marine energy application, bathymetry variations create strong velocity fluctuations in the water column. Experiments showed that wide cylindrical obstacles generate large velocity fluctuations, like those measured at sea. In order to study the effects of these fluctuations on the turbine behaviour, an experimental set-up has been developed in the circulating tank of Ifremer in Boulogne-sur-mer by positioning a cylinder and a turbine in its wake. Simultaneous PIV measurements give access to the flow velocity upstream of the turbine. Velocity and efforts are compared in terms of cross-correlation, coherence and their spectral content is studied. Results show that the turbine loads follow velocity...
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Ano: 2018 URL: https://archimer.ifremer.fr/doc/00482/59334/62112.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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PIV measurements combined with the motion tracking technique to analyze flow around a moving porous structure ArchiMer
Druault, Philippe; Germain, Gregory; Facq, Jean-valery.
To gain a better understanding of the fluid–structure interaction and especially when dealing with a flow around an arbitrarily moving body, it is essential to develop measurement tools enabling the instantaneous detection of moving deformable interface during the flow measurements. A particularly useful application is the determination of unsteady turbulent flow velocity field around a moving porous fishing net structure which is of great interest for selectivity and also for the numerical code validation which needs a realistic database. To do this, a representative piece of fishing net structure is used to investigate both the Turbulent Boundary Layer (TBL) developing over the horizontal porous moving fishing net structure and the turbulent flow passing...
Tipo: Text Palavras-chave: Unsteady turbulent flow; Particle Image Velocimetry; Oscillating structure; Fishing structure.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00271/38216/36479.pdf
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Tidal Energy ”Round Robin” Tests Comparisons between towing tank and circulating tank results ArchiMer
Gaurier, Benoit; Germain, Gregory; Facq, Jean-valery; Johnstone, C.m.; Grant, A.d.; Day, A.h.; Nixon, E.; Di Felice, F.; Costanzo, M..
One key step of the industrial development of a tidal energy device is the testing of scale prototype devices within a controlled laboratory environment. At present, there is no available experimental protocol which addresses in a quantitative manner the differences which can be expected between results obtained from the different types of facilities currently employed for this type of testing. As a consequence, where differences between results are found it has been difficult to confirm the extent to which these differences relate to the device performance or to the test facility type. In the present study, a comparative ”Round Robin” testing programme has been conducted as part of the EC FP VII MaRINET program in order to evaluate the impact of...
Tipo: Text Palavras-chave: ”Round Robin” Test; Experimental Trials; Marine Current Energy; Horizontal Axis Marine Turbine.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00270/38163/36298.pdf
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Vers une caractérisation réaliste des conditions de fonctionnement des hydroliennes ArchiMer
Germain, Gregory; Maganga, Fabrice; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas; Pinon, Grégory; Rivoalen, Elie; Etancelin, Jean-matthieu.
This paper presents experimental results of tests carried out in order to investigate the hydrodynamics of marine current turbines and to build an experimental database used to validate the numerical developments conducted to characterize the flow perturbations induced by marine current turbines. For that purpose, we used a tri-bladed horizontal axis turbine. Particular attention is paid to the flow characteristic effects (velocity gradient, flow orientation, flow turbulence intensity level) on the performance of a 0.70 m diameter turbine. The main interest is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines. Analyses are made from Laser Doppler Velocimeter measurements (velocity and turbulence...
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Ano: 2010 URL: http://archimer.ifremer.fr/doc/00021/13263/10310.pdf
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Visualisation 3D du phénomène de bullage autour de deux modèles d’étraves ArchiMer
Mallat, Bachar; Germain, Gregory; Billard, Jy; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas.
The bubble sweep-down phenomenon around oceanographic research vessels generates acoustic disturbances. This phenomenon has affected the acoustic surveys for many years and is still a significant issue. The reason is that neither towing tank trials nor numerical simulations are able to properly address this phenomenon. We proposed a specific experimental protocol in a wave and current circulating tank allowing a 3D visualization of the bubble sweep-down phenomenon around two ship models with different bow geometries. Visualisations and Particle Image Velocimetry (PIV) measurement results both obtained in the bow vicinity of the two ship models are presented in this paper. These results allow a better representation of the phenomenon compare to previous...
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Ano: 2016 URL: http://archimer.ifremer.fr/doc/00412/52332/53117.pdf
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Wake effects on marine current turbines ArchiMer
Pinon, Gregory; Germain, Gregory; Mycek, Paul; Gaurier, Benoit; Rivoalen, Elie; Cherfils, Jean-marc; Facq, Jean-valery; Bacchetti, Thomas.
Tipo: Text
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00141/25202/23310.pdf
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Wave and current flume tank of IFREMER at Boulogne-sur-mer. Description of the facility and its equipment ArchiMer
Gaurier, Benoit; Germain, Gregory; Facq, Jean-valery; Bacchetti, Thomas.
This document presents the wave and current flume tank of IFREMER at Boulogne-sur-mer. This facility is unique in Europe because of its size and capabilities. The experimental working section is 4m wide by 2m deep and 18m long. Two pumps with a total power of 500kW enable the 700m3 of fresh water to move with a maximum velocity of 2.2m/s. Wave can be superimposed to the current using a dedicated wavemaker. It can be located at an upstream of downstream surface position in order to generate wave propagating with or against the current. Additional specific experimental devices are used in the laboratory as well, such as: Laser Doppler Velocimeter, Acoustic Doppler Velocimeter, Particles Image Velocimetry, underwater and aerial Qualysis Motion Tracking system...
Tipo: Text Palavras-chave: Fluid mechanics; Hydrodynamics; Experimental trials; Wave and current flume tank; Ifremer; Boulogne-surmer.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00470/58163/60672.pdf
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