Дисертації з теми "Hydrodynamique tidale"
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Le, Pevedic Arnaud. "Études des interactions entre herbiers de zostères, hydrodynamique et dynamique sédimentaire dans une lagune semi-fermée : cas du Bassin d'Arcachon." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0041.
Seagrass meadows provide numerous ecosystem services and constitute a fundamental biological component for the sustainability of coastal environments. Over the past decades, the surface colonized by seagrasses has drastically declined globally, reducing their capacity to regulate hydrodynamic conditions and sediment fluxes. In this context, this work aims to better understand the response of hydro-sedimentary processes to the decline of intertidal seagrass in a shallow coastal lagoon. For this purpose, the Arcachon lagoon (France), extensively colonized by seagrass meadows (Zostera noltei and Zostera marina), was used as a study area. This analysis was conducted through a numerical modeling approach that required the preliminary development and implementation of a hydro-bio-sedimentary modeling platform, consisting of four coupled models (flow model, wave model, sediment transport model, and seagrass growth model), all accounting for the effect of vegetation. Specific attention was paid to the implementation of vegetation in the wave and sediment models, utilizing combined numerical, field, and laboratory experiments. The impact of seagrass decline was first studied on hydrodynamics, revealing significant changes in tidal hydrodynamics and the wave regime, especially an intensification in bottom current velocities by 100% and wave height by 50% on the tidal flats. Further investigation into the relative influence of seagrass decline and morphological evolutions of the inlet on tidal hydrodynamics showed that vegetation loss was the main factor influencing the modification of current velocities inside the lagoon. In response to the decline of Zostera spp. and the subsequent intensification of hydrodynamic conditions, this environment underwent significant changes in sediment dynamics. Modification of erosion and deposition fluxes resulted in suspended sediment concentrations 3 to 6 times higher in the areas where vegetation decreased the most. Seagrass decline also impacted sediment transport between the lagoon and the open ocean, as well as among different areas of the lagoon, leading to the redistribution of the different sediment classes and altering the composition of the seabed sediment. The tidal flats located along the coastlines accreted and became siltier, while those in the center of the lagoon eroded and became sandier. In particular, our results demonstrated that seagrass decline was the primary contributor to the observed bathymetric changes in the lagoon. Finally, potential evolutions of marine phanerogams were investigated, considering various consequences of climate change such as sea level rise and increase of temperature. For this analysis, special consideration was given to generating environmental forcing that reproduces potential temperature and water level conditions by 2050. Seagrass biomass exhibited contrasting responses to these processes, clearly dependent on multiple environmental factors (depth, hydrodynamic exposure, renewal time). We also showed that, beyond global warming, it is the increase in frequency and intensity of extreme temperature events that are expected to induce the most significant changes in seagrass biomass
Lo, Brutto Ottavio. "Energy management in a tidal farm. Application to the Alderney Race (Raz Blanchard)." Caen, 2016. http://www.theses.fr/2016CAEN2037.
Interest in Marine Renewable Energies (MREs) is growing worldwide because they are seen as a potential solution to reduce the emission of greenhouse gases. Among the different types of MRE tidal current energies are the most attractive. France has the second European production potential of electrical energy from tidal currents. The Alderney Race (Raz Blanchard in French) capitalizes about half of the national resource. Two of the main issues for the commercial development of tidal farms is the optimization of the turbines layout for maximizing the producible energy and the energy management for optimizing the energy production. These aspects depend on the wake effect and on the control of the electrical conversion chain. The objectives of this dissertation are the development of an optimization tool to maximize the producible energy of a tidal farm and the improvement of the control of the electrical chain. To this scope, an analytical model of the wake effect in a park is developed and validated. Moreover, different types of optimization algorithms are compared to solve the tidal farm layout optimization problem. The optimization tool is presented and tested in one site in the Alderney Race. Finally, all the components of the electrical conversion chain are modelled and different strategies to maximize the electrical production of the tidal farm are compared. A complete electrical model including all the components and the control are implemented to test the dynamic behavior of a hypothetical tidal farm subject to the changes in tidal speed in a site in the Alderney Race and to grid disturbances
Alastal, Khalil. "Ecoulements oscillatoires et effets capillaires en milieux poreux partiellement saturés et non saturés : applications en hydrodynamique côtière." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0039/document.
In this thesis, we study hydrodynamic oscillations in porous bodies (unsaturated or partially saturated), due to tidal oscillations of water levels in adjacent open water bodies. The focus is on beach hydrodynamics, but potential applications concern, more generally, time varying and oscillating water levels in coupled systems involving subsurface / open water interactions (natural and artificial beaches, harbor dykes, earth dams, river banks, estuaries). The tidal forcing of groundwater is represented and modeled (both experimentally and numerically) by quasi-static oscillations of water levels in an open water reservoir connected to the porous medium. Specifically, we focus on vertical water movements forced by an oscillating pressure imposed at the bottom of a soil column. Experimentally, a rotating tide machine is used to achieve this forcing. Overall, we use three types of methods (experimental, numerical, analytical) to study the vertical motion of the groundwater table and the unsaturated flow above it, taking into account the vertical head drop in the saturated zone as well as capillary pressure gradients in the unsaturated zone. Laboratory experiments are conducted on vertical sand columns, with a tide machine to force water table oscillations, and with porous cup tensiometers to measure both positive pressures and suctions along the column (among other measurement methods). Numerical simulations of oscillatory water flow are implemented with the BIGFLOW 3D code (implicit finite volumes, with conjugate gradients for the matrix solver and modified Picard iterations for the nonlinear problem). In addition, an automatic calibration based on a genetic optimization algorithm is implemented for a given tidal frequency, to obtain the hydrodynamic parameters of the experimental soil. Calibrated simulations are then compared to experimental results for other non calibrated frequencies. Finally, a family of quasi-analytical multi-front solutions is developed for the tidal oscillation problem, as an extension of the Green-Ampt piston flow approximation, leading to nonlinear, non-autonomous systems of Ordinary Differential Equations with initial conditions (dynamical systems). The multi-front solutions are tested by comparing them with a refined finite volume solution of the Richards equation. Multi-front solutions are at least 100 times faster, and the match is quite good even for a loamy soil with strong capillary effects (the number of fronts required is small, no more than N≈ to 20 at most). A large set of multi-front simulations is then produced in order to analyze water table and flux fluctuations for a broad range of forcing frequencies. The results, analyzed in terms of means and amplitudes of hydrodynamic variables, indicate the existence, for each soil, of a characteristic frequency separating low frequency / high frequency flow regimes in the porous system
Renaud, Florent. "Dynamics of the Tidal Fields and Formation of Star Clusters in Galaxy Mergers." Phd thesis, Université de Strasbourg, 2010. http://tel.archives-ouvertes.fr/tel-00508301.
Chalumeau, Julien. "Modélisation numérique de la circulation côtière : application au transport des méduses dans les Pertuis Charentais." Thesis, La Rochelle, 2014. http://www.theses.fr/2014LAROS005/document.
The Pertuis Charentais are an interconnected ecosystems site where ocean currents play a key role. A high resolution tidal model was developed in this thesis in order to understand the main features of the hydrodynamic flows inside the Pertuis. Two topics were put forward in this study. First, a new tide model for the Pertuis Charentais was build up and validated by using different datasets: tide gauge records, measurements of currents by ADCP and satellite images. A new approach to model calibration was developed by comparing the observed position of the waterline, the boundary between land and water, with that predicted by the model. Secondly, the transport and bloom-like aggregation of the Rhizostoma jellyfish populations were simulated numerically. The jellyfish proliferation and stranding are a source of socio-economic problems. Two types of jellyfish behavior, active and passive were simulated. The tidal currents and typical meteorological forcing were taken into account. The results show that the individual behavior of swimming jellyfish is an adaptive response to abiotic factors for jellyfish survival
Michelet, Nicolas. "Modélisation numérique de l'impact d'une ferme hydroliennes sur les conditions hydrodynamiques et sédimentaires du Passage du Fromveur en Mer d'Iroise." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC237/document.
In spite of a present only emerging operational development along the coast of France, the extraction of the kinetic energy of tidal currents by turbines appears as a promising solution to contribute locally to the energetic transition of insulary territories that are not connected to the continental electricity grid, with limited power needs, and are located in protected and touristic natural areas with a visual heritage to preserve. This doctoral thesis was devoted to the three-dimensional numerical modelling of the hydrodynamic and sedimentary impacts induced by horizontal-axis turbines deployed within the pilot site of the Fromveur Strait, in the natural marine Iroise park, off western Brittany. Numerical simulations are performed with the oceanographic model ROMS (Regional Ocean Modelling System) modified to integrate a theoretical actuator-disk sub-model that assimilates the device to a porous disc opposing the flow with a force equal to the turbine’s thrust. This method was assessed against laboratory measurements within the wake of a porous disc with a diameter (D) of 0.1 m immersed in a permanent flow. A spatial resolution as small as D/10 was required to reproduce observations. After a numerical convergence study at full scale, ROMS was applied, using a nested grid approach targetted towards the Fromveur Strait, to examine wake interactions and cumulative effects within an array of height turbines of 10-m-diameter expected to fulfill the energy need of the island of Ushant. The array layout followed the commonly recommended staggered configuration with respective longitudinal and lateral spacings of 10D and 5D. During spring tidal conditions, the misalignment of the peak flood flow enhanced the wake interactions, reducing by about 15% the array power production in comparison with the peak ebb flow. This lack of power production capacity was lowered to 2% by reducing the lateral spacing to 3D. ROMS predictions were finally exploited to address the influence of this last array of turbines on the local sediment dynamics. Main effects were expected on (i) the deposition of sediments with diameter over 2 mm within the turbine wakes and (ii) the setting in motion of gravels with a diameter of 5 cm between the wakes
Robin, Nicolas. "Morphodynamique des systèmes de flèches sableuses : étude comparative entre les embouchures tidales de l’Archipel de St Pierre et Miquelon et de la côte ouest du Cotentin (Manche)." Caen, 2007. http://www.theses.fr/2007CAEN2059.
The main objective of this thesis is to understand the formation and the evolution of sandy spits and tombolos using various spatio-temporal scales. In this perspective, two field sites were chosen, the Pointe d’Agon (Normandy) and the tombolo of Miquelon-Langlade (archipelago of St Pierre and Miquelon). The pointe d’Agon is a complex spit that has on its distal part several well-defined hooks. A new mechanism of formation of this type of morphology is proposed on the basis of a relation between the dynamics of a surf bar, migrating on an ebb delta, and the shoreline. The spit elongates in an intermittent way, in parallel of the extension of the sedimentary platform which supports it. The topographic monitoring of one of these bars indicates that it migrates with a mean speed of 35 m / year over several years. However, speed fluctuations appear to a shorter scale because its kinematics is strictly correlated with wave height. A significant height of 0. 7 m is necessary to induce bar migration. On the scale of the process, the movement takes place essentially during the surf action. The formation and the geometry of the Miquelon-Langlade tombolo is due to two important factors, the presence of available important sedimentary stock and the existence of different hydro-meteorological conditions between both coasts. The west coast presents generalized erosion in opposition to the accretion of the east coast. This evolution suggests a possible reopening of the tombolo in the short-term
Le, Dissez Aurélie. "Modélisation numérique des écoulements tidaux en milieux peu profonds : application à l'étude de l'hydrodynamique du Bassin d'Arcachon." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13181.
Latapy, Alexa. "Influence des modifications morphologiques de l'avant-côte sur l'hydrodynamisme et l'évolution du littoral des Hauts-de-France depuis le XIXe siècle." Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0554.
In coastal environment, interactions between morphodynamic, oceanographic and anthropic processes (acting over different timescales) control coastal systems evolution. This thesis is focused on long-term trends to determine the influence not only of human activities, but also the impact of climate change. Along the Northern coast of France, water level measurements were carried out since the early 19th century and tidal records were stored in the French Hydrographic Service (Shom) archives. At the same time that these measurements were conducted, hydrographic surveys were made for mapping the seabed of the coastal zone where tidal sand banks are common, forming linear shore-parallel or slightly oblique massive sand bodies. To determine long-term trends, digitization and analysis of these historical records were undertaken, enabling to reconstruct past sea-level changes and assess changes in sand bank morphology and position. Analysis of long tidal records suggests significant changes in tidal levels and a strong variability in the main tidal constituents. Moreover, analyses of bathymetry changes shows significant morphological variations across the shoreface since the 19th century, which are largely due to sand bank mobility. Numerical modelling of wave propagation and tidal circulation was performed using the TELEMAC suite of models to relate the observed changes in shoreface and nearshore morphology with possible variations in hydrodynamic processes. Under eroding conditions, an acceleration of tidal currents and an increase in wave height are obtained. Conversely, accumulation leads to an hydrodynamic regime weakening with a decrease in current velocity and to more wave energy dissipation in the nearshore. This study highlights the role of morphological feedbacks between nearshore morphology and coastal hydrodynamics. The identification of these feedbacks mechanisms at a secular time scale is important to assess potential drivers of coastal changes
Bourgoin, Adrien. "Modélisation de la turbulence engendrée par la morphologie dans le Raz Blanchard : approche régionale avec TELEMAC-LES." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC205/document.
Nowadays tidal currents are considered a promising renewable energy source. Many worldwide projects involve the installation of different types of marine current energy converters. The characterisation of marine resources is therefore essential to increase efficiency of energy production. Areas with high hydroturbine potential are particularly subject to multi-scale turbulence, ranging from small vortices able to cause large fatigue loads, to large vortices capable of disrupting turbine production. A better knowledge of the generation of these eddies and their propagation is essential. This is the purpose of the ANR/FEM THYMOTE project (Turbulence, Hydrolienne, Modélisation, Observations et TEsts en bassin) studying one of the most promising sites in Europe: the Alderney Race. One of the questions raised concerns the ability of large morphological structures on the seabed to produce eddies. The adopted method uses a 3D regional model to cover the area occupied by these bedforms.Regional models such as TELEMAC-3D use a turbulent URANS (Unsteady Reynolds Averaged Navier Stokes) closure, with for example the $k-\varepsilon$. This approach does not allow a detailed description of the instability of turbulence. However, thanks to the increase in computing resources, the large scale method (LES) becomes feasible. This is based on flow filtering, and consists of simulating only the largest turbulence scales, whereas the smaller ones are modeled. The TELEMAC-3D code was modified during this thesis in order to introduce this turbulent closure. The code developed allows free surface flows to be simulated over a wide range of scales from turbulence to tidal propagation. The TELEMAC-LES code has been validated on the basis of experimental results from the literature. It is then used to study turbulent flows in the Alderney Race using a nesting strategy. The LES method allows a detailed description of the turbulence of these environments. It finally leads to the identification of energetic vortex structures, and thus the definition the most appropriate zones for the installation of tidal turbines
Ait, Mohammed Mahrez. "Etude des tuyères composites pour une conception optimale d'une hydrolienne à axe horizontal." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0002/document.
Against the backdrop of the increasing scarcity of non-renewable fossil resources and climate change, the energy problem has become a worldwide issue. Hence, the exploitation of new renewable energy sources becomes a worldwide goal of primary importance. The concept of the underwater turbine, called tidal current turbine, designates the device which allows the conversion of the kinetic energy produced by marine currents in electric energy. This research study examines the problems related to the design of horizontal axis tidal current turbines. The present study shows that the world of marine propellers, sometimes entirely left out by the designers of tidal current turbines, presents an interesting avenue of research with regard to the hydrodynamic behaviour of tidal current turbines. Certain designers of tidal current turbines use a duct and hold that the addition of the duct contributes to the improvement of the hydrodynamic performance. Therefore, the study of the hydrodynamic benefits of ducted turbine using a constant overall cross-section than the bare turbine was the starting point of the present research work. In order to meet the needs of the manufacturers of tidal current turbines, which is generally linked to a problem of mass gain, composite materials present a considerable asset on account of their excellent «mass/resistance» and «mass/rigidity» relations. A structural design of ducted tidal current turbines using composite materials has therefore been examined. Hence, the design of a composite duct which yields the best «power/mass» ratio has been proposed. The duct of the tidal current turbine is especially confronted by the impacts due to its particular position. The impact damage aspect has also been examined in detail in the present research study
Caulet, Charles. "Les plages sableuses en environnement macro-tidal : de l'influence de la pente sur les processus morphodynamiques." Thesis, Brest, 2018. http://www.theses.fr/2018BRES0079/document.
This PhD work is focused on the morphodynamic of a pocket beach, located in a macrotidal environment. The beach type is intermediate, with a low tide terrace. The study is based on in situ observations, collected during field campaigns organized during the PhD. The objective is to characterize the beach slope impact on hydrodynamics processes and beach morphology. The water levels dynamic, infragravity waves propagation and turbulence generation in the swash zone, are examined and linked to the beach slope variability.The empirical formulations proposed in the literature show large under-estimations of water levels in the site. Empirical formulations adapted to the beach are proposed.The characteristic break slope presents along the cross-shore profile of low tide terrace beaches is studied. The variability of the break slope location is relevant to explain the short term accommodation of the beach. Under incident wave energy, the location of the beach slope moves shoreward, allowing higher wave dissipation by the low tide terrace. Nevertheless, the reflective part is reduced, which leads to a vulnerable state of the upper beach under strong forcing associated with high tide. The location of the beach slope is found to be a good indicator of the beach vulnerability under a given wave forcing. It provides valuable information in the globalized beach erosion context
Moreau, Martin. "Comportement d'une hydrolienne carénée à double axe vertical dans une diversité de conditions d'écoulement en mer et en bassin d'essais." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN028.
Limiting human-caused global warming requires, among other adaptations, a substantial reduction of fossil fuel use and a widespread electrification based on low greenhouse gas emission production systems. In this context, harnessing the tidal current energy and other marine renewable energy sources has gained interest for the last decade, which lead to the first offshore tests for several tidal energy converter concepts. Among them, the first 1 megawatt ducted twin vertical axis tidal turbine prototype, developed by HydroQuest, was tested off the northern coast of Brittany, France, from 2019 to 2021. In the prospect of the next turbine generations, the company wants to improve its experimental and numerical design tools to gain confidence in its capacity to predict the full-scale performance and loads from the experiments at reduced-scale. That can only be done by comparing the results obtained at sea to those obtained in the laboratories to assess the potential scale effects. Therefore, we first analyse the measurements at sea to characterise the behaviour of the prototype. Then, we study the response of a 1/20 scale model of that prototype tested in the Ifremer wave and current flume tank in Boulogne-sur-mer, France. We consider many flow conditions, increasing the complexity from idealised towards more realistic conditions. Beyond the comparison between reduced- and full-scale results, the analyses presented in that thesis also aim at better understanding the influence of each of the tidal current flow characteristics on the ducted turbine. In more details, from power performance, loads and wake measurements, we study the effects of the incident flow shear, of the relative flow direction, of the turbulence generated by bathymetry obstacles and of surface waves on the model response. The results show that the average power performance is rather insensitive to the incident flow conditions whereas the power and load fluctuations can be strongly affected. Finally, we discuss the scale effects on the results by comparing the power performance, the loads and the wake results in the tank with those obtained on the prototype at sea. The results allow to refine the evaluation of the correction needed at reduced-scale to predict the power performance at full-scale, mainly due to Reynolds number difference. Even if the loads and the wake results seem less affected by the viscous effects, a detailed comparison with the full-scale results would require improvements on the measurements at sea to better quantify the potential scale effects. Those improvements may be implemented in the coming years with the launch of the next generation of twin vertical axis tidal turbines
Nachtane, Mourad. "Énergies marines renouvelables et étude des performances des matériaux composites : cas d'une hydrolienne." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0010.
Recently, Renewable Marine Energies (RME) has emerged as a tremendous opportunity for a real ecological and industrial choice to meet the growing demands for energy and also to fight global warming. The study conducted in this thesis is with in this framework of research and is focused on the investigation of one of the most promising categories of RMEs which is tidal current turbine. A new hydrofoil for the turbine was designed using BEM (Blade Element Momentum) methods and CFD (Computational Fluid Dynamics) calculations with improved hydrodynamic efficiency. Furthermore, a series of numerical studies were conducted to investigate and examine the damage behavior of composite materials under critical loadings by developing DLOAD and VUMAT routines. This numerical study assisted in understanding the problems of structural lightening, resistance to fatigue and impact loading, and other degradation phenomena of themechanical properties of a composite turbine in severe marine environments and solving the needs of the manufactures. Moreover, study about the dynamic behavior of a composite/composite bonded assembly was also conducted because joint assembly plays a vital role in reducing the mass of the structure which is of extreme relevance in the field of marine and offshore structures. Another important obstacle regarding the application of composite and bonded structures in marine was the control of hygro-mechanical coupling. Therefore in this context, additional campaign of tests was carried out on bonded composite specimens by studying the hygrothermal effect on their dynamic behavior at different deformation rates using Hopkinson bar method. This hybrid study of hygro-thermal effect of the dynamic properties of the bonded composites will aid in optimization of the structures and to move into the commercial phase with a substantial gain in LCOE (Levelized Cost of Energy) in future
Grondeau, Mikaël. "Modélisation des effets de sillage d'une hydrolienne avec la méthode de Boltzmann sur réseau." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC257/document.
In a global context where access to energy is a major problem, the exploitation of tidal currents with tidal turbines is of particular interest. Flows in areas with high energy potential suitable for the installation of tidal turbines are often highly turbulent. However, the ambient turbulence has a strong impact on the surrounding hydrodynamics and the turbine operation. A precise prediction of turbulence and wake is fundamental to the optimization of a tidal farm. A numerical model of the flow around the turbine must therefore be accurate and take into account the ambient turbulence. A tool based on the Lattice Boltzmann Method (LBM) is used for this purpose, in combination with a Large Eddy Simulation (LES) approach. The LBM is an unsteady method for modelling fluid flows. A synthetic turbulence method is implemented to take into account the ambient turbulence of tidal sites. Complex geometries, potentially in motion, are modelled using the Immersed Boundary Method (IBM). The implementation of a wall model is carried out in order to reduce the cost of the simulations. These tools are then used to model a turbine in a turbulent environment. The calculations, performed at two different turbulence rates, are compared with experimental and NS-LES results. The LBM-LES models are then used to analyze the wake of the turbine. In particular, it is observed that a low turbulence rate has a significant impact on the propagation of tip-vortices
Quilfen, Victor. "Dynamique de plages sableuses enclavées à la pointe Bretagne." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1146/document.
In this thesis, waves and neap-spring tide action on sandy embayed beaches constrained by rocky headlands is studied. A complementary approach combining numerical modeling and in situ measurements is used. Two deterministic model based on major physical processes (hydrodynamics, hydro-sedimentary and morphodynamics) present in the coastal zone and averaged over the water height (2DH) have been selected. XBeach (Roelvink et al., 2009) employs a finite difference scheme and incorporates some specific processes such as a roller, wave groups and the associated bound long wave and a undertow. TELEMAC (Hervouet, 2007) is a finite element scheme. Nearby sandy embayed beaches of La Palue and Lostmarc'h (Crozon Peninsula, Finistère) have been chosen for their complex bathymetry (rip channels, tombolo) and geometry (headlands, small island). One year of in situ measurements (topographical surveys, ADV velocimeters) between septembre 2014 and september 2015 has been undertaken, with different waves and tide climates.Firstly, the overall dynamics of embayed beaches built schematically in the form of a rectangular indentation has been caught. Especially, subtidal sandbar formation under the influence of waves, neap-spring tide and rocky headlands has been studied through several sets of numerical simulations.Secondly, hydrodynamic modelling on the embayed beaches of La Palue and Lostmarc'h has been made with the aim of study influence of waves characteristics (height, period and direction) and indentation's ones (headlands length, spacing between headlands, headlands inclination) on the prediction of currents. A simulation using finite element scheme (TELEMAC) has been achieved and compared to those using finite difference scheme (XBeach). XBeach currents predictions at two locations on the beaches of La Palue and Lostmarc'h over the period from the 21st January 2015 to the 23rd January 2015 have been compared to in situ measurements to validate the model. Whereupon, a numerical hydro-sedimentary simulation (using XBeach) over a full lunation from the 1st September 2015 to the 29th September 2015 has been undertaken on these two beaches, with the aim of study the intensity and direction of sediment flux (instantaneous and residual) for various waves and tide climates and for different morphological areas. This work has helped to highlight the dynamics features of embayed beaches compared to open beaches ones, such as headland sand bypassing, but also similarities. Moreover, XBeach morphodynamics predictions have been compared to in situ measurements for different model setup.Thirdly, after an in-depth statistical analysis of wave climates over a 7 year period offshore of La Palue and Lostmarc'h beaches, the morphodynamic impact of extreme storm waves (ten-yearly and fifty-yearly) combined to a sea level rise induced by climatic change on a cross-shore bottom profile south of La Palue has been estimated through a numerical study (using XBeach)
Genco, Marie-Laure. "Les marées dans l'Océan atlantique : modélisation et bilan énergétique." Grenoble 1, 1993. http://www.theses.fr/1993GRE10009.
Mercier, Philippe. "Modélisation de la turbulence engendrée par la morphologie du fond dans le Raz Blanchard : approche locale avec la LBM-LES." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC206/document.
Renewable energy development calls for exploitation of new energy resources. Tidal stream power harvesting is now close to the industrialisation step. Still, turbulent hydrodynamic conditions at tidal sites are not well understood. This thesis aims to investigate the local scale effect of sea bottom roughnesses on energetic vortex generation with computational fluid simulations using the lattice Boltzmann method. This method is highly indicated for unsteady flow simulations of complex domains. First, the physical phenomena involved in vortex emission around canonical macroroughnesses are described. Vortex merging is identified in the generation process of energetic vortices. Then, such physical events are reproduced in the case of environmental flow simulations using a real seabed morphology. These simulations are validated on in situ measured data, and lead to a better understanding of the sea bottom effect on tidal stream site turbulence. They demonstrate the role of geological faults on the local turbulence
Aelbrecht, Denis. "Étude expérimentale de la rectification d'un écoulement alternatif pariétal en milieu tournant et de la turbulence d'une couche d'Ekman oscillante : application aux courants de marée en Manche orientale." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10103.
Vladoiu, Anda Claudia. "Turbulence in the Western Mediterranean Sea." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS558.
The processes characterising turbulence in the Western Mediterranean Sea were identified and quantified using microstructure measurements. The focus was on the Sicily Channel, a hotspot for turbulent mixing and a key region for water mass transformations. It modulates the heat and salt transport from the Eastern to the Western Mediterranean Basins and exhibits a large range of dynamical regimes. Turbulence is driven by the strong shear associated to the flow of Levantine Intermediate Waters (LIW) which is constricted by the bathymetry, and by internal wave breaking of tidal origin. A strong contrast was observed between the two deep passages in the channel. The mixing efficiency variability was investigated in the context of mechanically driven turbulence over a wide spectrum of turbulence intensities. A finescale parameterisation for the turbulent kinetic energy dissipation rate was validated for weak to moderate turbulence intensity. The vertical turbulent diffusive fluxes computed from the measurements allowed an assessment of the water mass property changes incurred in the channel. The analysis was extended to all the stations sampled in the Western Mediterranean, where the relative impact of double diffusion and mechanical turbulence on heat, salt and buoyancy fluxes, as well as on the LIW, was investigated
Huguet, Jean-Rémy. "Dynamique hydro-sédimentaire en milieu portuaire : application au port de plaisance de La Rochelle." Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS034.
Ports are presents on all maritime and river fronts of the world, and represent major interfaces in the development of territories. The natural siltation of these calm areas can obstruct waterways and prevent these infrastructures from fulfilling their primary function as a shelter for boats. This often involves the implementation of expensive and time-consuming dredging operations to restore depths compatible with navigation. Les Minimes marina (La Rochelle, France), which is one of the largest marinas on the Atlantic coast, is not spared by this phenomenon and requires dredging activities for a large part of the year. In response to this problem, the marina and La Rochelle University, has wanted to understand better the natural environment and the processes leading to the accumulation of sediments in the marina. By combining an instrumental in situ approach with operational numerical modelling, the objective of this thesis was, therefore, to characterise the hydro-sedimentary dynamics of the area. Quantification of the impact of floating structures (boats, pontoons) on marina hydrodynamics was firstly carried out. The second field of study aimed to study the circulation of water masses and their renewal about the effect of wind and tide. The observations collected made it possible to study spatial and temporal sediment dynamics, under the action of wind, tide and waves. Thus, numerous siltation control measures have been implemented and analysed to provide solutions and research perspectives in view with siltation and dredging management