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| Registros recuperados: 39 | |
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| Ikhennicheu, Maria; Gaurier, Benoit; Druault, Philippe; Germain, Gregory. |
| The present study aims at investigating turbulence characteristics in high flow velocity areas like those suitable for marine energy application. The Reynolds number, based on the rugosity height and mean flow velocity, is rather high: . For that purpose, experiments are carried out in a flume tank with as high as achievable in Froude similitude (in the tank: and ). Obstacles are canonical wall-mounted elements chosen to be representative of averaged bathymetric variations: a cube and a cube followed by an inclined floor. First, the wake topology past a canonical wall-mounted cube is illustrated from PIV measurements. Results show a flow behaviour already observed in the literature but for different upstream conditions ( and turbulence intensity). Second,... |
| Tipo: Text |
Palavras-chave: Turbulence; Experimental trials; Wall-mounted obstacles; PIV; POD; Quadrant method. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00449/56050/57570.pdf |
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| Xie, X. H.; Cuypers, Y.; Bouruet-aubertot, P.; Ferron, Bruno; Pichon, Annick; Lourenco, A.; Cortes, Norbert. |
| Microstructure and fine-scale measurements collected in the central Bay of Biscay during the MOUTON experiment are analyzed to investigate the dynamics of internal waves and associated mixing. Large-amplitude internal tides (ITs) that excite internal solitary waves (ISWs) in the thermocline are observed. ITs are dominated by modes 3 and 4, while ISWs projected on mode 1 that is trapped in the thermocline. Therein, ITs generate a persistent narrow shear band, which is strongly correlated with the enhanced dissipation rate in the thermocline. This strong dissipation rate is further reinforced in the presence of ISWs. Dissipation rates during the period without ISWs largely agree with the MacKinnon-Gregg scaling proposed for internal wavefields dominated by a... |
| Tipo: Text |
Palavras-chave: Internal tides; Solitary waves; Turbulence; Bay of Biscay. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00151/26232/24299.pdf |
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| Aghanim, N.; Akrami, Y.; Alves, Mir; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Ballardini, M.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Benabed, K.; Bernard, J. -p.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Bucher, M.; Burigana, C.; Calabrese, E.; Cardoso, J. -f.; Carron, J.; Chary, R. -r.; Chiang, H. C.; Colombo, L. P. L.; Combet, C.; Crill, B. P.; Cuttaia, F.; De Bernardis, P.; De Zotti, G.; Delabrouille, J.; Delouis, Jean Marc; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Dore, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Ensslin, T. A.; Eriksen, H. K.; Falgarone, E.; Fantaye, Y.; Fernandez-cobos, R.; Ferriere, K.; Finelli, F.; Forastieri, F.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Genova-santos, R. T.; Gerbino, M.; Ghosh, T.; Gonzalez-nuevo, J.; Gorski, K. M.; Gratton, S.; Green, G.; Gruppuso, A.; Gudmundsson, J. E.; Guillet, V.; Handley, W.; Hansen, F. K.; Helou, G.; Herranz, D.; Hivon, E.; Huang, Z.; Jaffe, A. H.; Jones, W. C.; Keihanen, E.; Keskitalo, R.; Kiiveri, K.; Kim, J.; Krachmalnicoff, N.; Kunz, M.; Kurki-suonio, H.; Lagache, G.; Lamarre, J. -m.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Le Jeune, M.; Levrier, F.; Liguori, M.; Lilje, P. B.; Lindholm, V.; Lopez-caniego, M.; Lubin, Pm; Ma, Y. -z.; Macias-perez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marcos-caballero, A.; Maris, M.; Martin, Pg; Martinez-gonzalez, E.; Matarrese, S.; Mauri, N.; Mcewen, J. D.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-deschenes, M. -a.; Molinari, D.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Natoli, P.; Pagano, L.; Paoletti, D.; Patanchon, G.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Polastri, L.; Polenta, G.; Puget, J. -l.; Rachen, J. P.; Reinecke, M.; Remazeilles, M.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rubino-martin, J. A.; Ruiz-granados, B.; Salvati, L.; Sandri, M.; Savelainen, M.; Scott, D.; Sirignano, C.; Sunyaev, R.; Suur-uski, A. -s.; Tauber, J. A.; Tavagnacco, D.; Tenti, M.; Toffolatti, L.; Tomasi, M.; Trombetti, T.; Valiviita, J.; Vansyngel, F.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wandelt, B. D.; Wehus, I. K.; Zacchei, A.; Zonca, A.. |
| Observations of the submillimetre emission from Galactic dust, in both total intensity I and polarization, have received tremendous interest thanks to the Planck full-sky maps. In this paper we make use of such full-sky maps of dust polarized emission produced from the third public release of Planck data. As the basis for expanding on astrophysical studies of the polarized thermal emission from Galactic dust, we present full-sky maps of the dust polarization fraction p, polarization angle psi, and dispersion function of polarization angles ?. The joint distribution (one-point statistics) of p and N-H confirms that the mean and maximum polarization fractions decrease with increasing N-H. The uncertainty on the maximum observed polarization fraction, (max) =... |
| Tipo: Text |
Palavras-chave: Polarization; Magnetic fields; Turbulence; Dust; Extinction; Local insterstellar matter; Submillimeter: ISM. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76632/77786.pdf |
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| Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal. |
| A growth and survival model of the early life stages was run along virtual drift trajectories tracked in a hydrodynamic model to simulate the annual recruitment process of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). These biophysical simulations concerning three different years were analysed in order to investigate the influence of environment and spawning dynamics on the survival of larvae and juveniles. The location of space-time survival windows suggested major environmental mechanisms involved in simulated recruitment variability at the different scales - retention of larvae and juveniles in favourable habitats over the shelf margins and turbulence effects. These small-scale and meso-scale mechanisms were related to the... |
| Tipo: Text |
Palavras-chave: Turbulence; Retention; Recruitment; Physical biological interactions; Larval survival; IBM; Biscay; Anchovy. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3423.pdf |
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| Bouruet-aubertot, Pascale; Cuypers, Yannis; Ferron, Bruno; Dausse, Denis; Menage, Olivier; Atmadipoera, Agus; Jaya, Indra. |
| Microstructure measurements were performed along two sections through the Halmahera Sea and the Ombai Strait and at a station in the deep Banda Sea. Contrasting dissipation rates (𝜖) and vertical eddy diffusivities (K z ) were obtained with depth-averaged ranges of ∼[9×10−10−10−5] W kg− 1 and of ∼[1×10−5−2×10−3] m2 s− 1, respectively. Similarly, turbulence intensity, I=ϵ/(νN2) with ν the kinematic viscosity and N the buoyancy frequency, was found to vary seven orders of magnitude with values up to 107. These large ranges of variations were correlated with the internal tide energy level, which highlights the contrast between regions close and far from internal tide generations. Finescale parameterizations of 𝜖 induced by the breaking of... |
| Tipo: Text |
Palavras-chave: Turbulence; Internal tides; Vertical mixing; Parameterization; Indonesian seas; Microstructure measurements. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55240/56792.pdf |
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| Defontaine, Sophie; Sous, Damien; Morichon, Denis; Verney, Romaric; Monperrus, Mathilde. |
| The present paper reports on a series of field experiments aiming to characterise the functioning of a man-engineered strongly forced salt-wedge estuary: the lower estuary of the Adour river, France. Bottom-moored velocity measurements and surface boat surveys have been performed under low river discharge conditions, for both neap and spring tides, in order to provide a well-documented reference framework to understand the dynamics of water masses, turbulence and suspended particulate matter (SPM) transport in the lower estuary. An additional campaign has been carried out in high river discharge conditions. This first documented in-situ study of the Adour lower estuary demonstrates its variability in terms of hydrological regimes, from salt-wedge to... |
| Tipo: Text |
Palavras-chave: Salt-wedge estuary; Estuarine circulation; Stratification; Turbulence; Suspended particles transport; Adour river. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70049/67987.pdf |
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| Medina, Olmo Duran; Schmitt, Francois G.; Calif, Rudy; Germain, Gregory; Gaurier, Benoit. |
| The correlation between the flow turbulence and the performances of a marine current turbine is studied. First, the incoming flow encountered in the flume tank is characterized in the framework of fully developed turbulent cascades in the inertial range. The Reynolds number, the Kolmogorov dissipation scale and the integral scale, are estimated from flow measurements. The intermittency of the turbulence is characterized in the lognormal multifractal framework, and the influence of the turbulent flow on the turbine power is assessed. The rotor speed control unit characteristics used for the turbine regulation induces non-negligible effects on the turbine behavior under fluctuations loads. Even if the power spectrum does not reveal any scale invariance, a... |
| Tipo: Text |
Palavras-chave: Marine energy; Turbulence; Multifractal energy cascade; Intermittency; Turbine power production; High frequency data rate. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00385/49620/50134.pdf |
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| Brinkkemper, J. A.; Lanckriet, T.; Grasso, Florent; Puleo, J. A.; Ruessink, B. G.. |
| Current coastal-evolution models generally lack the ability to accurately predict bed level change in shallow (<~2 m) water, which is, at least partly, due to the preclusion of the effect of surface-induced turbulence on sand suspension and transport. As a first step to remedy this situation, we investigated the vertical structure of turbulence in the surf and swash zone using measurements collected under random shoaling and plunging waves on a steep (initially 1:15) field-scale sandy laboratory beach. Seaward of the swash zone, turbulence was measured with a vertical array of three Acoustic Doppler Velocimeters (ADVs), while in the swash zone two vertically spaced acoustic doppler velocimeter profilers (Vectrino profilers) were applied. The vertical... |
| Tipo: Text |
Palavras-chave: Turbulence; Plunging breakers; Swash; Laboratory experiment. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00277/38812/37538.pdf |
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| Ikhennicheu, Maria; Germain, Gregory; Druault, Philippe; Gaurier, Benoit. |
| In high flow velocity areas like those suitable for marine energy application, bathymetry variations create strong velocity fluctuations in the water column. It is therefore essential to characterize the turbulence evolution in the wake of seabed elements which may impact the loads on tidal turbines. For that purpose, experiments are carried out in a flume tank with Re as high as achievable in Froude similitude, with bathymetry variations experimentally represented with various wall-mounted square elements of height H: a cylinder or a cube as unitary obstacles and combinations of these elements followed by an inclined floor to resemble smooth bathymetry changes. The onset flow is a simple boundary layer profile with height 1.3 H and a low turbulence... |
| Tipo: Text |
Palavras-chave: Turbulence; Experimental trials; Wall-mounted obstacles; PIV; LDV; Marine energy. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00502/61356/64997.pdf |
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| Mycek, Paul; Gaurier, Benoit; Germain, Gregory; Pinon, Gregory; Rivoalen, Elie. |
| The future implantation of second generation marine current turbine arrays depends on the understanding of the negative interaction effects that exist between turbines in close proximity. This is especially the case when the turbines are axially aligned one behind another in the flow. In order to highlight these interaction effects, experiments were performed in a flume tank on 3-bladed 1/30th scale prototypes of horizontal axis turbines. This work focuses on the interactions between two horizontal axis marine current turbines, axially aligned with the upstream flow. Thrust and power coefficients function of the rotation speed of the downstream device are presented. Besides, the wake of each turbine is characterised so as to explain their behaviour. A... |
| Tipo: Text |
Palavras-chave: Marine current turbine; Performance; Wake; Turbulence; Array; Tidal turbine. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00175/28644/27110.pdf |
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| Grasso, Florent; Ruessink, B. G.. |
| Waves breaking in the shallow surf zone near the shoreline inject turbulence into the water column that may reach the bed to suspend sediment. Breaking-wave turbulence in the surf zone is, however, poorly understood, which is one of the reasons why many process-based coastal-evolution models predict coastal change during severe storms inadequately. Here, we use data collected in two natural surf zones to derive a new parameterization for the stability function C-mu that determines the magnitude of the eddy viscosity nu(t) in two-equation turbulent-viscosity models, nu(t) = C(mu)k(2)/epsilon, where k is turbulent kinetic energy and epsilon is the turbulence dissipation rate. In both data sets, the ratio of turbulence production to dissipation is small... |
| Tipo: Text |
Palavras-chave: Eddy viscosity; Field measurements; Parameterization; Production; Surf zone; Turbulence. |
| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00114/22512/20204.pdf |
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| Donis, Daphne; Holtappels, Moritz; Noss, Christian; Cathalot, Cecile; Hancke, Kasper; Polsenaere, Pierre; Wenzhoefer, Frank; Lorke, Andreas; Meysman, Filip J. R.; Glud, Ronnie N.; Mcginnis, Daniel F.. |
| The quantification of benthic fluxes with the aquatic eddy correlation (EC) technique is based on simultaneous measurement of the current velocity and a targeted bottom water parameter (e.g., O2, temperature). High-frequency measurements (64 Hz) are performed at a single point above the seafloor using an acoustic Doppler velocimeter (ADV) and a fast-responding sensor. The advantages of aquatic EC technique are that 1) it is noninvasive, 2) it integrates fluxes over a large area, and 3) it accounts for in situ hydrodynamics. The aquatic EC has gained acceptance as a powerful technique; however, an accurate assessment of the errors introduced by the spatial alignment of velocity and water constituent measurements and by their different response times is... |
| Tipo: Text |
Palavras-chave: Turbulence; Boundary layer; Fluxes; Instrumentation/sensors; Optimization; Experimental design. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00275/38577/37102.pdf |
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| Ikhennicheu, Maria; Germain, Gregory; Druault, Philippe; Gaurier, Benoit. |
| In high flow velocity areas like those suitable for tidal applications, turbulence intensity is high and flow variations may have a major impact on tidal turbines behaviour. Large boils that can be observed at the sea surface are emitted from the sea floor and may interact with the tidal turbines. These boils have then to be characterized. The Reynolds number, based on the rugosity height and the mean flow velocity, is rather high in this context: Re ¼ 2:5 107. For that purpose, experiments are carried out in a flume tank with Re as high as achievable in Froude similitude (in the tank: Re ¼ 2:5 105 and Fr ¼ 0:23) in order to study coherent flow structures emitted behind seabed obstacles. The obstacle is here a canonical square wall-mounted cylinder chosen... |
| Tipo: Text |
Palavras-chave: Turbulence; Experimental trials; Wall-mounted cylinder; PIV; LDV; POD; Lamb-Oseen. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60527/64189.pdf |
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| Togneri, Michael; Pinon, Grégory; Carlier, Clement; Choma Bex, Camille; Masters, Ian. |
| Turbulence is a crucial flow phenomenon for tidal energy converters (TECs), as it influences both the peak loads they experience and their fatigue life. To best mitigate its effects we must understand both turbulence itself and how it induces loads on TECs. To that end, this paper presents the results of blade element momentum theory (BEMT) simulations of flume-scale TEC models subjected to synthetic turbulent flows. Synthetic turbulence methods produce three-dimensional flowfields from limited data, without solving the equations governing fluid motion. These flowfields are non-physical, but match key statistical properties of real turbulence and are much quicker and computationally cheaper to produce. This study employs two synthetic turbulence generation... |
| Tipo: Text |
Palavras-chave: BEMT; SEM; Sandia; Tidal turbines; Turbulence; Simulation. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00501/61248/64828.pdf |
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| Registros recuperados: 39 | |
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