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| Registros recuperados: 11 | |
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| Bouhoubeiny, Elkhadim; Germain, Gregory; Druault, Philippe. |
| Flow field measurements behind a rigid cod-end and a moving bottom trawl are conducted using Time Resolved PIV method. This method is based on an image acquisition rate allowing the time resolved sampling of the vortex shedding phenomenon. Based on such measurements, the main flow characteristics around fishing net structure are investigated. Moreover, the vortex shedding frequency phenomenon associated with both the rigid cod-end and the moving bottom trawl is analyzed. We then present the analysis of the instability of the shear layer separating a moving trawl having 3 degrees of freedom. Using also the Proper Orthogonal Decomposition (POD) for such investigation, it is demonstrated the effectiveness of this procedure to extract not only the large scale... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00022/13280/10324.pdf |
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| Bouhoubeiny, Elkhadim; Druault, Philippe. |
| To enhance the temporal resolution of the PIV measurements of pseudo-periodic turbulent flows, Proper Orthogonal Decomposition (POD) has been previously used to time interpolate PIV database. In this note, it is demonstrated that such POD interpolation is equivalent to the classical mathematical interpolation when dealing with the whole POD eigenfunctions, since POD is a linear transform. In fact, the POD-based time interpolation is only valid for the large scale structures of the flow. The advantage of using POD procedure resides in its efficiency in extracting the dominant flow structures. In this sense, other interpolation methods such as turbulent filtering procedures could provide similar results. To cite this article: E. Bouhoubeiny, P Druault, C R.... |
| Tipo: Text |
Palavras-chave: Fluid mechanics; Particle image velocimetry; Proper orthogonal decomposition; Large scale flow structures. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00021/13199/10314.pdf |
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| 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. |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00116/22716/20683.pdf |
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| Bouhoubeiny, Elkhadim; Germain, Gregory; Druault, Philippe. |
| Flow field measurements past a fixed rigid cod-end structure and past a porous fishing net structure are conducted using Time-Resolved PIV method. The rigid cod-end is first used to characterize finely the wake flow. Proper Orthogonal Decomposition (POD) is then applied in order to extract the large scale energetic vortices of the flow from the measured velocity field. It is then observed that the first POD modes are associated to the Karman's type flow structure of vortex shedding. It is shown that the characteristics of the wake flow behind the rigid cod-end flow configuration compare quite well with previous ones obtained from bluff cylinder or sphere wake analyzes. Second, PIV measurements are performed around a non-rigid bottom trawl which is free to... |
| Tipo: Text |
Palavras-chave: Fishing gear; PIV measurements; Vortex shedding; Proper Orthogonal Decomposition. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00027/13820/11046.pdf |
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| Druault, Philippe; Bouhoubeiny, Elkhadim; Germain, Gregory. |
| Particle image velocimetry (PIV) measurements are made to investigate the boundary layer developing over a modeled bottom trawl. The random motion of the fishing net structure as well as the flexibility and the porosity of this structure means that it is not enable to access the main characteristics of such a flow, using classical post-processing mathematical tools. An innovative post-treatment tool based on proper orthogonal decomposition (POD) is then developed to extract the mean velocity flow field from each available PIV instantaneous unsteady velocity field. In order to do so, the whole available velocity database is used to compute POD eigenfunctions and the first POD modes are identified as representing the mean flow field. It is then possible to... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19935/17776.pdf |
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| Bouhoubeiny, Elkhadim; Germain, Gregory; Druault, Philippe. |
| The work presented in this paper is carried out under the HydroPêche project with the aim to develop a tool for an automatic optimisation of trawl in order to minimize the drag of the gear. One of the aspects of this project is the experimental investigation of the turbulent flow around bottom trawls. For that purpose, Particle Image Velocimetry measurements in a flume tank are implemented to access to the two-dimensional velocity field around a bottom trawl. Having an important experimental database allows not only the calibration of numerical models aiming at simulating the flow around a fishing net but also the validation of numerical simulation results. Such experimental technique has the advantage in accessing the turbulent flow field and then allows... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00021/13268/10315.pdf |
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| Bouhoubeiny, Elkhadim. |
| The objective of this study is to experimentally determine the flow characteristics governing the hydrodynamic behaviour of fishing gear and in particular of a bottom trawl. This porous structure is characterized by horizontal and curved parts, but also a final part of spherical shape named codend. In order to characterize the different types of flow observed over this porous structure, Particle Image Velocimetry (PIV) measurements are carried around several kind of devices, representative of all or part bottom trawl. In particular, a complete 1/10 scaled bottom trawl and a sheet of net are used to characterize the development of the boundary layer above the horizontal part of this porous structure. The sheet of net is also used to characterize the wake of... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00092/20276/17921.pdf |
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| Bouhoubeiny, Elkhadim; Druault, Philippe; Germain, Gregory. |
| Time-Resolved Particle Image Velocimetry (PIV) measurements are performed to investigate the hydrodynamic flow interaction with a representative piece of fishing net structure. Using the advanced post-processing mathematical tool based on Proper Orthogonal Decomposition, the phase averaged mean properties of turbulent flows are extracted from PIV database, demonstrating the existence of a Turbulent Boundary Layer (TBL) flow developing all around the sheet of net. The results also show that the mesh opening and so the turbulent flow passing through the structure are strongly influenced by the structure oscillations. This work allows us to demonstrate that the drag computation of fishing gear, commonly based on uniform velocity, needs to consider not only... |
| Tipo: Text |
Palavras-chave: Fishing net structure; Hydrodynamics; PIV; Turbulent boundary layer flow. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00184/29552/27878.pdf |
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| Registros recuperados: 11 | |
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