Letteratura scientifica selezionata sul tema "Offshore structures, CFD"
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Articoli di riviste sul tema "Offshore structures, CFD"
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Vasilyev, Leonid, Konstantinos Christakos e Brian Hannafious. "Treating Wind Measurements Influenced by Offshore Structures with CFD Methods". Energy Procedia 80 (2015): 223–28. http://dx.doi.org/10.1016/j.egypro.2015.11.425.
Testo completo
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Peric, Milovan, e Volker Bertram. "Trends in Industry Applications of Computational Fluid Dynamics for Maritime Flows". Journal of Ship Production and Design 27, n. 04 (1 novembre 2011): 194–201. http://dx.doi.org/10.5957/jspd.2011.27.4.194.
Testo completoAbstract (sommario):
This paper surveys developments in Computational Fluid Dynamics (CFD) applications for maritime structures (ships, propellers, and offshore structures) over the past decade. Progress is significant in integrating the process chain, particularly more automated model generation. Increased hardware power and progress in various aspects of the flow solvers allow more sophisticated applications and wider scope of applications. Selected examples taken from industry and research applications show the increasing importance of CFD in earlier design stages.
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A. Rahman, Mohd Asamudin, Muhammad Nadzrin Nazri, Ahmad Fitriadhy, Mohammad Fadhli Ahmad, Erwan Hafizi Kasiman, Mohd Azlan Musa, Fatin Alias e Mohd Hairil Mohd. "A Fundamental CFD Investigation of Offshore Structures for Artificial Coral Reef Development". CFD Letters 12, n. 7 (30 luglio 2020): 110–25. http://dx.doi.org/10.37934/cfdl.12.7.110125.
Testo completo
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Van den Abeele, F., e J. Vande Voorde. "Stability of offshore structures in shallow water depth". International Journal Sustainable Construction & Design 2, n. 2 (6 novembre 2011): 320–33. http://dx.doi.org/10.21825/scad.v2i2.20529.
Testo completoAbstract (sommario):
The worldwide demand for energy, and in particular fossil fuels, keeps pushing the boundaries of offshoreengineering. Oil and gas majors are conducting their exploration and production activities in remotelocations and water depths exceeding 3000 meters. Such challenging conditions call for enhancedengineering techniques to cope with the risks of collapse, fatigue and pressure containment.On the other hand, offshore structures in shallow water depth (up to 100 meter) require a different anddedicated approach. Such structures are less prone to unstable collapse, but are often subjected to higherflow velocities, induced by both tides and waves. In this paper, numerical tools and utilities to study thestability of offshore structures in shallow water depth are reviewed, and three case studies are provided.First, the Coupled Eulerian Lagrangian (CEL) approach is demonstrated to combine the effects of fluid flowon the structural response of offshore structures. This approach is used to predict fluid flow aroundsubmersible platforms and jack-up rigs.Then, a Computational Fluid Dynamics (CFD) analysis is performed to calculate the turbulent Von Karmanstreet in the wake of subsea structures. At higher Reynolds numbers, this turbulent flow can give rise tovortex shedding and hence cyclic loading. Fluid structure interaction is applied to investigate the dynamicsof submarine risers, and evaluate the susceptibility of vortex induced vibrations.As a third case study, a hydrodynamic analysis is conducted to assess the combined effects of steadycurrent and oscillatory wave-induced flow on submerged structures. At the end of this paper, such ananalysis is performed to calculate drag, lift and inertia forces on partially buried subsea pipelines.
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Decorte, Griet, Alessandro Toffoli, Geert Lombaert e Jaak Monbaliu. "On the Use of a Domain Decomposition Strategy in Obtaining Response Statistics in Non-Gaussian Seas". Fluids 6, n. 1 (7 gennaio 2021): 28. http://dx.doi.org/10.3390/fluids6010028.
Testo completoAbstract (sommario):
During recent years, thorough experimental and numerical investigations have led to an improved understanding of dynamic phenomena affecting the fatigue life and survivability of offshore structures, e.g., ringing and springing and extreme wave impacts. However, most of these efforts have focused on modeling either selected extreme events or sequences of highly nonlinear waves impacting offshore structures, possibly overestimating the actual load to be experienced by the structure. Overall, not much has been done regarding short-term statistics. Although clear non-Gaussian statistics and therefore higher probabilities of extreme waves have been observed in random seas due to wave–wave interaction phenomena, which can impact short-term statistics for the structural load, they have not been studied extensively regarding the assessment of the dynamic behavior of offshore structures. Computational fluid dynamics (CFD) models have shown their viability for studying wave–structure interaction phenomena. Despite the continuously increasing computational resources, these models remain too computationally demanding for applications to the large spatial domains and long periods of time necessary for studying short-term statistics of non-Gaussian seas. Higher-order spectral (HOS) models, on the other hand, have been proven to be efficient and adequate in studying non-Gaussian seas. We therefore propose a one-way domain decomposition strategy, which takes full advantage of the recent advances in CFD and of the computational benefits of HOS. When applying this domain decomposition strategy, it appeared to be possible to deduce response statistics regarding the impact of nonlinear wave–wave interactions.
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Decorte, Griet, Alessandro Toffoli, Geert Lombaert e Jaak Monbaliu. "On the Use of a Domain Decomposition Strategy in Obtaining Response Statistics in Non-Gaussian Seas". Fluids 6, n. 1 (7 gennaio 2021): 28. http://dx.doi.org/10.3390/fluids6010028.
Testo completoAbstract (sommario):
During recent years, thorough experimental and numerical investigations have led to an improved understanding of dynamic phenomena affecting the fatigue life and survivability of offshore structures, e.g., ringing and springing and extreme wave impacts. However, most of these efforts have focused on modeling either selected extreme events or sequences of highly nonlinear waves impacting offshore structures, possibly overestimating the actual load to be experienced by the structure. Overall, not much has been done regarding short-term statistics. Although clear non-Gaussian statistics and therefore higher probabilities of extreme waves have been observed in random seas due to wave–wave interaction phenomena, which can impact short-term statistics for the structural load, they have not been studied extensively regarding the assessment of the dynamic behavior of offshore structures. Computational fluid dynamics (CFD) models have shown their viability for studying wave–structure interaction phenomena. Despite the continuously increasing computational resources, these models remain too computationally demanding for applications to the large spatial domains and long periods of time necessary for studying short-term statistics of non-Gaussian seas. Higher-order spectral (HOS) models, on the other hand, have been proven to be efficient and adequate in studying non-Gaussian seas. We therefore propose a one-way domain decomposition strategy, which takes full advantage of the recent advances in CFD and of the computational benefits of HOS. When applying this domain decomposition strategy, it appeared to be possible to deduce response statistics regarding the impact of nonlinear wave–wave interactions.
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Wu, Yanling. "Numerical tools to predict the environmental loads for offshore structures under extreme weather conditions". Modern Physics Letters B 32, n. 12n13 (10 maggio 2018): 1840039. http://dx.doi.org/10.1142/s0217984918400390.
Testo completoAbstract (sommario):
In this paper, the extreme waves were generated using the open source computational fluid dynamic (CFD) tools — OpenFOAM and Waves2FOAM — using linear and nonlinear NewWave input. They were used to conduct the numerical simulation of the wave impact process. Numerical tools based on first-order (with and without stretching) and second-order NewWave are investigated. The simulation to predict force loading for the offshore platform under the extreme weather condition is implemented and compared.
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Dymarski, Paweł, Ewelina Ciba e Tomasz Marcinkowski. "Effective Method for Determining Environmental Loads on Supporting Structures for Offshore Wind Turbines". Polish Maritime Research 23, n. 1 (1 gennaio 2016): 52–60. http://dx.doi.org/10.1515/pomr-2016-0008.
Testo completoAbstract (sommario):
Abstract This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load.
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Dervilis, Nikolaos, A. C. W. Creech, A. E. Maguire, Ifigeneia Antoniadou, R. J. Barthorpe e Keith Worden. "An SHM View of a CFD Model of Lillgrund Wind Farm". Applied Mechanics and Materials 564 (giugno 2014): 164–69. http://dx.doi.org/10.4028/www.scientific.net/amm.564.164.
Testo completoAbstract (sommario):
Reliability of offshore wind farms is one of the key areas for the successful implementation of these renewable power plants in the energy arena. Failure of the wind turbine (WT) in general could cause massive financial losses but especially for structures that are operating in offshore sites. Structural Health Monitoring (SHM) of WTs is essential in order to ensure not only structural safety but also avoidance of overdesign of components that could lead to economic and structural inefficiency. A preliminary analysis of a machine learning approach in the context of WT SHM is presented here; it is based on results from a Computational Fluid Dynamics (CFD) model of Lillgrund Wind farm. The analysis is based on neural network regression and is used to predict the measurement of each WT from the measurements of other WTs in the farm. Regression model error is used as an index of abnormal response.
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Rahman, Shaikh Atikur, Zubair Imam Syed, John V. Kurian e M. S. Liew. "Structural Response of Offshore Blast Walls under Accidental Explosion". Advanced Materials Research 1043 (ottobre 2014): 278–82. http://dx.doi.org/10.4028/www.scientific.net/amr.1043.278.
Testo completoAbstract (sommario):
Adequate blast resistant barriers are requisite to protect personnel and critical systems from the consequences of an accidental explosion and subsequent fire. Many of the blast walls currently installed in offshore structures were designed using simplified calculation approaches like Single Degree of Freedom models (SDOF) as recommended in many design guidelines. Over simplified and idealised explosion load used for response calculation and design of blast wall can lead to inadequate or overdesign of offshore blast walls. Due to lack of presence of a well-accepted design guidelines supported by extensive study, the protection provided by the conventional blast walls for offshore structures can be inadequate. In-depth understanding of structural response of blast walls under different blast loading can provide better design practice of blast walls for adequate protection. In this study, structural responses of conventional offshore blast walls were investigated. A computation fluid dynamics (CFD) approach was used to predict effect of different explosions on the barrier walls and non-linear finite elements analyses were performed to study the behaviour of the blast-loaded walls under different explosions. Effect of different parameters related to blast wall and accidental explosions were investigated to gain detail understanding of structural behaviour of typical steel blast wall.
Tesi sul tema "Offshore structures, CFD"
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Olaoye, Abiodun Timothy. "CFD simulation of long slender offshore structures at high Reynolds number". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122262.
Testo completoAbstract (sommario):
Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 129-131).
Slender cylindrical structures are common in many offshore engineering applications such as floating wind turbines and subsea risers. These structures are vulnerable to flow-induced vibrations under certain environmental conditions which impacts their useful life. Flow-induced vibrations have been widely studied both experimentally and numerically especially at low Reynolds number. However, many questions remain unanswered in detail regarding the effects of high Re on structural responses and fluid-structure interaction (FSI) phenomena such as lock-in for different design configurations. Furthermore, under realistic environmental conditions, the oncoming flow velocity profile may not be uniform. In such scenarios, effects of large changes in Re along span on nature of structural responses may be significant.
This research project is focused on computational fluid dynamics (CFD) simulation of slender structures under realistic oncoming ocean currents with relatively higher Reynolds number (Re >/- 10,000) compared to existing literature. Computational methods for investigating FSI phenomena are limited by high Reynolds number, complex flow profiles, low mass ratio and large aspect ratio of structures. Despite these challenges, numerical approach potentially offers more detailed analysis and ease of parameter tuning to investigate unique cases too expensive to conduct in experiments. Therefore, advances in research is increasingly supported by numerical modeling. In the framework of Fourier Spectral/hp element method implemented in NEKTAR code, an entropy-based viscosity method (EVM) was employed to account for turbulence effects not captured by the numerical grid and fictitious added mass method was utilized in the structure solver to handle low mass ratio problems.
Also, the mapping-enabled smoothed profile method (SPM) in addition to already stated techniques was used to simulate cases involving buoyancy modules. A thorough verification and validation of the current algorithms was carried out for stationary cylinders with uniform cross-sections, flexibly-mounted rigid cylinders and flexible cylinders. Major contributions include EVM enabled simulations of dynamic responses of flexibly-mounted rigid cylinders with low mass ratio in higher Reynolds number uniform flows (Re = 140,000) compared with existing literature thereby yielding numerically novel response maps. The new results provide more insights on the role of Re in amplitude responses and FSI phenomena associated with vortex-induced vibrations in practical applications. Another major contribution is the investigation in detail of complex flows past a flexible cylinder at Re[subscript max] The relatively large change in Re along span revealed new fluid-structure energy transfer behavior in linearly and exponentially sheared flows.
by Abiodun Timothy Olaoye.
Ph. D. in Mechanical Engineering and Computation
Ph.D.inMechanicalEngineeringandComputation Massachusetts Institute of Technology, Department of Mechanical Engineering
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Abdolmaleki, Kourosh. "Modelling of wave impact on offshore structures". University of Western Australia. School of Mechanical Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0055.
Testo completoAbstract (sommario):
[Truncated abstract] The hydrodynamics of wave impact on offshore structures is not well understood. Wave impacts often involve large deformations of water free-surface. Therefore, a wave impact problem is usually combined with a free-surface problem. The complexity is expanded when the body exposed to a wave impact is allowed to move. The nonlinear interactions between a moving body and fluid is a complicated process that has been a dilemma in the engineering design of offshore and coastal structures for a long time. This thesis used experimental and numerical means to develop further understanding of the wave impact problems as well as to create a numerical tool suitable for simulation of such problems. The study included the consideration of moving boundaries in order to include the coupled interactions of the body and fluid. The thesis is organized into two experimental and numerical parts. There is a lack of benchmarking experimental data for studying fluid-structure interactions with moving boundaries. In the experimental part of this research, novel experiments were, therefore, designed and performed that were useful for validation of the numerical developments. By considering a dynamical system with only one degree of freedom, the complexity of the experiments performed was minimal. The setup included a plate that was attached to the bottom of a flume via a hinge and tethered by two springs from the top one at each side. The experiments modelled fluid-structure interactions in three subsets. The first subset studied a highly nonlinear decay test, which resembled a harsh wave impact (or slam) incident. The second subset included waves overtopping on the vertically restrained plate. In the third subset, the plate was free to oscillate and was excited by the same waves. The wave overtopping the plate resembled the physics of the green water on fixed and moving structures. An analytical solution based on linear potential theory was provided for comparison with experimental results. ... In simulation of the nonlinear decay test, the SPH results captured the frequency variation in plate oscillations, which indicated that the radiation forces (added mass and damping forces) were calculated satisfactorily. In simulation of the nonlinear waves, the waves progressed in the flume similar to the physical experiments and the total energy of the system was conserved with an error of 0.025% of the total initial energy. The wave-plate interactions were successfully modelled by SPH. The simulations included wave run-up and shipping of water for fixed and oscillating plate cases. The effects of the plate oscillations on the flow regime are also discussed in detail. The combination of experimental and numerical investigation provided further understanding of wave impact problems. The novel design of the experiments extended the study to moving boundaries in small scale. The use of SPH eliminated the difficulties of dealing with free-surface problems so that the focus of study could be placed on the impact forces on fixed and moving bodies.
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Douteau, Louis. "CFD simulation with anisotropic mesh adaptation : application to floating offshore wind turbines". Thesis, Ecole centrale de Nantes, 2020. http://www.theses.fr/2020ECDN0003.
Testo completoAbstract (sommario):
Le calcul des performances et des efforts appliqués sur une éolienne offshore est actuellement réalisé à l'aide d’outils basés sur des approches quasi-statiques. Ces approches sont intéressantes pour leur vitesse de calcul, elles sont cependant perfectibles suivant la méthode de mise en oeuvre et suivant les cas de chargement étudiés. Une approche alternative consiste à utiliser la modélisation CFD. Cette thèse s’intéresse à des méthodes d’une haute précision, ayant le potentiel de fournir des écoulements et efforts précis. La plateforme logicielle hautement parallélisée ICI-tech est utilisée dans cette thèse. Elle se base sur une résolution des équations de Navier-Stokes dans une approche multi-échelle, effectuée à l’aide d’éléments finis stabilisés. La représentation des phases dans le domaine de calcul est réalisée grâce à une méthode frontières immergées. Des implémentations ont été réalisées dans ICI-tech afin de pouvoir simuler des éoliennes flottantes. L’interaction fluide-structure et un bassin de houle numérique ont notamment été considérés. Un processus de vérification et validation s’est intéressé au comportement du solveur dans des conditions reproduisant celles impactant des éoliennes flottantes. Le niveau de précision atteint par les écoulements à haut Reynolds et la propagation de champs de houle s’est avéré être décevant. L’influence du maillage anisotrope sur les résultats obtenus a été quantifiée. Plusieurs pistes visant à améliorer la précision des simulations ont été introduitesThe simulation of Floating Offshore Wind Turbines (FOWTs) is a tool to help this technology reach an industrial scale. Nowadays, low-precision numerical methods are used for the dimensioning of the structures, as they involve a reduced computational effort. This PhD thesis focused on the development of highly-accurate numerical methods, with a potential to provide a thin description of the flows and efforts around FOWTs. The simulations presented in this thesis have been realized on the highly-parallelized software platform ICI-tech. A resolution of the Navier- Stokes equations in a Variational MultiScale formulation is performed using Stabilized Finite Elements. The representation of the different phases in the computational domain is achieved using immersed boundary methods. Several numerical tools have been implemented in ICItech towards an application to the simulation of FOWTs. A fluid-structure interaction paradigm has been set up, and a numerical wave tank has been defined. Verification and validation studies have been realized to assess the solver results for environmental conditions representative of those observed for operating FOWT. The accuracy achieved for both the aerodynamics at high Reynolds numbers and the propagation of wave fields has been disappointing. The influence of the anisotropic meshing on the results presented has been quantified. Several options aiming at increasing the accuracy of the simulations have been discussed
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Motamed, Dashliborun Amir. "Performance of multiphase packed-bed reactors and scrubbers on offshore floating platforms: hydrodynamics, chemical reaction, CFD modeling and simulation". Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30439.
Testo completoAbstract (sommario):
Les systèmes flottants de production, stockage et de déchargement (FPSO) ont été introduits dans les secteurs d'exploitation des hydrocarbures offshore en tant qu'outils facilement déplaçables pour l’exploitation de champs de pétrole et de gaz de petites ‘a moyenne tailles ou lorsque ceux-ci sont éloignés des côtes ou en eaux profondes. Ces systèmes sont de plus en plus envisagés pour les opérations de traitement et de raffinage des hydrocarbures à proximité des sites d'extraction des réservoirs sous-marins en utilisant des laveurs et des réacteurs à lit fixe embarqués. De nombreuses études dans la littérature pour découvrir l'hydrodynamique de l'écoulement polyphasiques dans des lits garnis ont révélé que la maîtrise de tels réacteurs continue d’être un défi quant à leur conception /mise à l'échelle ou à leur fonctionnement. De plus, lorsque de tels réacteurs sont soumis à des conditions fluctuantes propres au contexte marin, l'interaction des phases devient encore plus complexe, ce qui entraîne encore plus de défis dans leur conception. Les travaux de recherche proposés visent à fournir des informations cruciales sur les performances des réacteurs à lit fixes à deux phases dans le cadre d'applications industrielles flottantes. Pour atteindre cet objectif, un simulateur de mouvement de navire de type hexapode avec des mouvements à six degrés de liberté a été utilisé pour simuler les mouvements des FPSO tandis que des capteurs à maillage capacitif (WMS) et un tomographe à capacitance électrique (ECT) couplés avec le lit garni ont permis de suivre en ligne les caractéristiques dynamiques locales des écoulements diphasiques. L'effet des inclinaisons et des oscillations de la colonne sur le comportement hydrodynamique des lits garnis biphasiques a été étudié, puis les résultats ont été comparés à leurs analogues terrestres correspondants (colonne verticale immobile). De plus, des stratégies opérationnelles potentielles ont été proposées pour atténuer la maldistribution des fluides résultant des oscillations du lit ainsi que pour intensifier le processus de réactions dans les réacteurs à lit fixe. Parallèlement aux études expérimentales, un modèle Eulérien CFD transitoire 3D a été développé pour simuler le comportement hydrodynamique de lits garnis polyphasiques sous des inclinaisons et des oscillations de colonnes. Enfin, pour compléter le travail expérimental, une étude systématique a été réalisée pour étudier les performances de capture de CO2 à base d'amines d’un laveur à garnissage (en vrac et structuré) émulant une colonne à bord des ...Floating production storage and offloading (FPSO) systems have been introduced to offshore hydrocarbon exploitation sectors as readily movable tools for development of small or remote oil and gas fields in deeper water. These systems are increasingly contemplated for onboard treatment and refining operations of hydrocarbons extracted from undersea reservoirs near extraction sites using embarked packed-bed scrubbers and reactors. Numerous efforts in the literature to uncover the hydrodynamics of multiphase flow in packed beds have disclosed that such reactors continue to challenge us either in their design/scale-up or their operation. Furthermore, when such reactors are subjected to marine conditions, the interaction of phases becomes even more complex, resulting in further challenges for design and scale-up. The proposed research aims at providing important insights into the performance of two-phase flow packed-bed reactors in the context of floating industrial applications. To achieve this aim, a hexapod ship motion simulator with six-degree-of-freedom motions was employed to emulate FPSO movements while capacitance wire mesh sensors (WMS) and electrical capacitance tomography (ECT) coupled with the packed bed scrutinized on-line and locally the two-phase flow dynamic features. The effect of column tilts and oscillations on the hydrodynamic behavior of multiphase packed beds was investigated and then the results were compared with their corresponding onshore analogs. Moreover, potential operational strategies were proposed to diminish fluid maldistribution resulting from bed oscillations as well as for process intensification of heterogeneous catalytic reactions in packed-bed reactors. In parallel with the experiment studies, a 3D transient Eulerian CFD model was developed to simulate the hydrodynamic behavior of multiphase packed beds under column tilts and oscillations. Ultimately, a systematic experimental study was performed to address the amine-based CO2 capture performance of packed-bed scrubbers on board offshore floating vessels/platforms. Apart from gaining a comprehensive knowledge on the influence of translational and rotational movements on multiphase flows in porous media, oil and gas sectors and ship industry would benefit from the results of this work for design and scale-up of industrial reactors and scrubbers.
Unité flottante de production, de stockage et de déchargement
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Liu, Yuanchuan. "A CFD study of fluid-structure interaction problems for floating offshore wind turbines". Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30597.
Testo completoAbstract (sommario):
As one of the fastest growing renewable energy sources, wind energy is playing an increasingly important part in addressing the climate change and energy crisis issues the world is currently facing. The abundance of wind resource in offshore areas makes them a popular choice for turbine installation. In the past few years, several floating wind projects have emerged where wind turbines are installed far offshore in deepwater sites on moored platforms. Compared to land-based or offshore fixed-bottom wind turbines, an FOWT is a fully coupled system where the wind turbine with flexible blades and the floating platform with its mooring system interact with each other in wind and waves, which makes old design tools inadequate. This work aims to develop a fully coupled high-fidelity aero-hydro-mooring-elastic analysis tool, and to better understand the sophisticated fluid-structure interactions for FOWTs. The numerical tool developed in this work takes advantage of the open source CFD toolbox OpenFOAM to accurately solve wind turbine aerodynamics and floating platform hydrodynamics, and utilises the open source MBD code MBDyn for structural dynamics within a multibody framework while modelling flexible bodies based on a nonlinear beam theory. Coupling of these two solvers is achieved by establishing an interface library to exchange data with the help of the TCP/IP protocol. Additionally, to tackle the complex mesh movement in FOWT simulations, a mesh motion solver is developed in OpenFOAM by combining the sliding mesh technique and the dynamic mesh morphing method. A mooring system analysis module comprising a quasi-static method and a lumped-mass based dynamic approach is also implemented to simulate mooring lines in an FOWT system. A series of test cases is firstly studied to validate the various features of the tool, including basic fluid flow solving, modelling of wind turbine aerodynamics, hydrodynamic analysis of a floating structure with its mooring system, dynamic analysis of a riser or mooring line and coupled analysis of flow induced vibration of a flexible beam. The developed tool is then applied to analyse FSI problems of FOWTs under three different scenarios. Firstly, a coupled aero-hydro-mooring analysis is carried out for the OC4 semisubmersible FOWT under regular waves and uniform wind speed. Blade flexibility is ignored, and mooring lines are solved using the quasi-static method. Interactions between the moored platform and the wind turbine are investigated, focusing on of platform motion on the aerodynamic performance of the wind turbine and the impacts of wind turbine aerodynamics on the responses of the floating platform and its mooring system. Subsequently, an aeroelastic analysis is conducted for the NREL 5-MW offshore wind turbine with flexible blades under uniform wind speed. Effects of blade flexibility on wind turbine aerodynamics and structural responses are studied using the developed CFD-MBD tool. The floating platform supporting the turbine is not directly modelled for simplicity and the influence of platform motion responses on the turbine are analysed via imposing a prescribed surge motion to the turbine base. Fully coupled aero-hydro-mooring-elastic analysis is lastly carried out for the OC4 semi-submersible FOWT under a combined wind/wave condition to demonstrate the capabilities of the developed CFD-MBD tool. Responses of the floating system are investigated in terms of platform hydrodynamics, mooring system dynamics, wind turbine aerodynamics and blade structural dynamics. Interactions between the FOWT and fluid flow are analysed by visualising results obtained via the CFD approach.
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Ercolanelli, Julien. "Étude numérique et expérimentale d'un système couplé stabilisateur et récupérateur d'énergie des vagues Experimental and numerical investigation of sloshing in anti-roll tank using effective gravity angle Experimental and numerical assessment of the performance of a new type passive anti-roll stabilisation system". Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0008.
Testo completoAbstract (sommario):
Le développement de Geps Techno est basé sur un concept innovant de structure flottante destinée à produire de l'énergie électrique à partir de plusieurs sources d'énergies marines renouvelables dont la source houlomotrice. Le système houlomoteur développé par Geps Techno repose sur la mise en circulation d'eau et la création d'un tourbillon en son sein. En profitant du phénomène de carène liquide, le concept est également déclinable en un système de stabilisation de navire ou de toute autre plateforme flottante. L'objectif à court terme de la société est le développement de cette technologie permettant la stabilisation et la récupération de l'énergie des vagues et pour lequel il reste des verrous technologiques à lever afin d'arriver à la viabilité et la rentabilité du système. Pour cela, Geps Techno a lancé en octobre 2015 le projet IHES (Integrated Harvesting Energy System) qui consiste à construire un démonstrateur de son concept de plateforme houlomotrice. Le projet IHES est un des projets de la feuille de route du plan "Navires écologiques" de la Nouvelle France Industrielle. Il est soutenu par Bpifrance dans le cadre du programme d'Investissements d'Avenir - Projets Industriels d'Avenir. Afin de maîtriser les objectifs de stabilisation et de récupération d'énergie, Geps Techno étudie les volets technologiques nécessaires permettant de passer de l'énergie disponible au niveau des vagues jusqu'à celle disponible au niveau de la turbine du houlomoteur. Les travaux de thèse soutenus par Fourestier en mai 2017 portaient sur un premier volet "Définition et contrôle des écoulements internes au système houlomoteur". A l'aide d'une modélisation des fluides numériques, ces derniers ont abouti à des modèles opérationnels caractérisant les écoulements internes. La présente thèse Cifre s'inscrit dans la continuité des travaux de Fourestier et traite d'un second volet "Modélisation du système couplé plateforme / houlomoteur". L'ensemble de ces travaux devra aboutir à un code de calcul opérationnel et corrélé à des résultats expérimentaux permettant d'étudier l'écoulement interne et le comportement du flotteur soumis à la houleGeps Techno's development is based on an innovative concept of a floating structure intended to produce electrical energy from several renewable marine energy sources, including wave power. The wave power system developed by Geps Techno is based on circulating water and creating a vortex within it. By taking advantage of the liquid hull phenomenon, the concept can also be used as a stabilization system for a ship or any other floating platform. The short-term objective of the company is the development of this technology allowing the stabilization and recovery of wave energy and for which there remain technological obstacles to be removed in order to achieve the viability and profitability of the system. To do this, in October 2015 Geps Techno launched the IHES (Integrated Harvesting Energy System) project, which consists of building a demonstrator of its wave power platform concept. The IHES project is one of the projects of the roadmap of the "Ecological ships" plan of New Industrial France. It is supported by Bpifrance within the framework of the Investments for the Future - Industrial Projects for the Future program. In order to master the objectives of stabilization and energy recovery, Geps Techno is studying the technological aspects necessary to switch from the energy available at wave level to that available at the wave turbine turbine. The Ph.D. thesis work supported by Fourestier in May 2017 focused on a first part "Definition and control of internal flows in the wave power system". Using CFD modeling, the latter resulted in operational models characterizing internal flows. This Cifre Ph.D. thesis follows on from Fourestier's work and deals with a second part "Modeling of the coupled platform / wave power system". All of this work should lead to an operational computer code correlated with experimental results making it possible to study the internal flow and the behavior of the float subjected to swell
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Allsop, Steven Christopher. "Hydrodynamic modelling for structural analysis of tidal stream turbine blades". Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/33219.
Testo completoAbstract (sommario):
The predictable nature of the tides offers a regular, reliable source of renewable energy that can be harnessed using tidal stream turbines (TSTs). The UK's practically extractable tidal stream energy resource has the potential to supply around 7 % of the country's annual electricity demand. As of 2016, the world's first commercial scale arrays have been deployed around the UK and France. The harsh nature of the marine operating environment poses a number of engineering challenges, where the optimal turbine design solution remains under investigation. In this thesis, a numerical model is developed to assess the power production and hydrodynamic behaviour of horizontal axis tidal turbines. The developed model builds upon well established and computationally efficient Blade Element Momentum Theory (BEMT) method for modern three-bladed wind turbines. The main novel contribution of this thesis is extending the application to an alternative design of a ducted, high solidity and open centre TST. A validation study using measurements from multiple different scale model experimental tank tests has proven the applicability of the model and suitability of the imposed correction factors. The analytical modifications to account for ducted flow were subsequently indirectly verified, where predictions of turbine power and axial thrust forces under optimal operating speeds were within 2 % of those using more advanced computational fluid dynamics (CFD) methods. This thesis presents a commercial application case of two turbines designed by OpenHydro, examining the BEMT performance with a sophisticated blade resolved CFD study. A comparison of results finds that the model is capable of predicting the average peak power to within 12 %, however it under predicts thrust levels by an average of 35 %. This study concludes that the model is applicable to ducted turbine configurations, but is limited in capturing the complex flow interactions towards the open centre, which requires further investigation. The computational efficiency of the newly developed model allowed a structural analysis of the composite blades, thus demonstrating it is suitable to effectively evaluate engineering applications. Stresses are seen to be dominated by flap-wise bending moments, which peak at the mid-length of the blade. This tool will further enable EDF to perform third party assessments of the different turbine designs, to aid decision making for future projects.
Atti di convegni sul tema "Offshore structures, CFD"
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Kara, M. C., J. Kaufmann, R. Gordon, P. P. Sharma e J. Y. Lu. "Application of CFD for Computing VIM of Floating Structures". In Offshore Technology Conference. Offshore Technology Conference, 2016. http://dx.doi.org/10.4043/26950-ms.
Testo completo
2
Jiang, Changqing, Ould el Moctar e Thomas E. Schellin. "Prediction of Hydrodynamic Damping of Moored Offshore Structures Using CFD". In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95935.
Testo completoAbstract (sommario):
Abstract Usually, mooring system restoring forces acting on floating offshore structures are obtained from a quasi-static mooring model alone or from a coupled analysis based on potential flow solvers that do not always consider nonlinear mooring-induced phenomena or fluid-structure interactions and the associated viscous damping effects. By assuming that only the mooring system influences the restoring force characteristics, the contribution of mooring-induced damping to total system damping is neglected. This paper presents a technique to predict hydrodynamic damping of moored structures based on coupling the dynamic mooring model with a Reynolds-averaged Navier-Stokes (RANS) equations solver. We obtained hydrodynamic damping coefficients using a least-square algorithm to fit the time trace of decay tests. We analyzed a moored offshore buoy and validated our predictions against experimental measurements. The mooring system consisted of three catenary chains. The analyzed response comprised the decaying oscillating buoy motions, the natural periods, and the associated linear and quadratic damping characteristics. Predicted motions, natural periods, and hydrodynamic damping generally well agreed to comparable experimental data.
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Cho, S., S. Hwang, J. Jung, H. Sung, B. Park e A. Vazquez-Hernandez. "Estimation of Wind and Current Load on Offshore Structures Using Wind Tunnels and CFD". In Offshore Technology Conference. Offshore Technology Conference, 2018. http://dx.doi.org/10.4043/28771-ms.
Testo completo
4
Atluri, Sampath, Allan Magee e Kostas Lambrakos. "CFD as a Design Tool for Hydrodynamic Loading on Offshore Structures". In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79502.
Testo completoAbstract (sommario):
Time-domain numerical integration of the rigid body equations of motion is a popular choice for analyzing the global motions of a single or multi-module floating platform. Potential flow theory cannot accurately account for all the hydrodynamic forces on certain components of the platform. However, for practical analysis, these members can be modeled as Morison members in the time-domain simulations. Computational Fluid Dynamics (CFD) can be used to calculate Morison coefficients for the given flow conditions on the exact geometry of the member. This paper presents the results from CFD simulations performed on several individual components of a floating platform (like heave plates, truss members etc.,) in realistic environment conditions. The procedure used for extracting the linear and non-linear coefficients from the total calculated hydrodynamic force is also explained. Results from CFD are compared to existing published experimental results. Differences between full-scale and model-scale results will be emphasized where important. Some of the advantages of using CFD as opposed to model tests are highlighted.
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Holmes, Samuel, Owen H. Oakley e Yiannis Constantinides. "Simulation of Riser VIV Using Fully Three Dimensional CFD Simulations". In 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92124.
Testo completoAbstract (sommario):
Fully three dimensional computational fluid dynamics (CFD) solutions are combined with structural models of a tensioned riser to predict riser vortex induced motion. The use of three dimensional CFD solutions overcomes many of the shortcomings of combining a series of strip or two dimensional simulations to calculate the fluid forces on the riser. Three dimensional vortex structures are treated correctly and straked risers and variations in angle of attack can be studied directly. The proposed method uses finite element methods that are tolerant of sparse meshes and high element aspect ratios. This allows economical solutions of large fluid domains while retaining the important features of the large fluid vortex structures which drive risers. Long risers can be treated with readily available computers and examples of simulations of riser with L/D over 1400 are given and compared with previously published experimental data. These examples are used to illustrate several points regarding the effects of the treatment of the riser structure as well as the efficacy of rotating frame or pinned riser experiments used to simulate sheared currents. The method can also be extended to sheared currents whose heading varies with depth.
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Corson, David, Steve Cosgrove, Paul R. Hays, Yiannis Constantinides, Owen H. Oakley, Harish Mukundan e Ming Leung. "CFD Based Hydrodynamic Databases for Wake Interference Assessment". In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49407.
Testo completoAbstract (sommario):
The interaction of the wake between pairs of long flexible cylindrical structures is of major consequence in the design of offshore oil and gas production facilities. Modern designs of these facilities often utilize arrays of flexible pipes (risers) extending from the mean water line to the mud-line and then to the subsea reservoir. As ocean currents interact with these structures, wakes are formed at the upstream structure and propagate to the downstream structure (a perturbed flow-field) resulting in a modified force on the downstream structure. This effect, known as the shielding effect, needs to be properly accounted for during the design of offshore facilities. Conservative yet realistic estimates of the effect of separation between the structures under a variety of ocean currents are sought. It is common industry practice to evaluate the clearance between a pair of long flexible cylindrical structures using a finite element based tool. Hydrodynamic loads are based on experiments on a pair of short rigid cylinders. Recent advances in Computational Fluid Dynamics (CFD) technology have made it cheaper and quicker to perform simulations of these conditions without compromising the underlying physics. This alternative is preferred to more expensive and time consuming physical prototype experiments. This paper presents the results of high resolution, time accurate CFD simulations used to understand and quantify the wake interaction between a straked cylinder and a cylinder mounted with the AIMS Dual Fin Splitter (ADFS). No prior experimental data were available for the riser configurations and conditions that were investigated. The simulations were performed using prototypic current velocities and geometries. This paper will describe the CFD technology used in detail. The paper will cover the model setup, the extent of and discretization of the model, the choice of time-step, the boundary conditions, and a discussion on the results from the simulation.
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Lu, Xin, Pankaj Kumar, Anand Bahuguni e Yanling Wu. "A CFD Study of Focused Extreme Wave Impact on Decks of Offshore Structures". In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23804.
Testo completoAbstract (sommario):
The design of offshore structures for extreme/abnormal waves assumes that there is sufficient air gap such that waves will not hit the platform deck. Due to inaccuracies in the predictions of extreme wave crests in addition to settlement or sea-level increases, the required air gap between the crest of the extreme wave and the deck is often inadequate in existing platforms and therefore wave-in-deck loads need to be considered when assessing the integrity of such platforms. The problem of wave-in-deck loading involves very complex physics and demands intensive study. In the Computational Fluid Mechanics (CFD) approach, two critical issues must be addressed, namely the efficient, realistic numerical wave maker and the accurate free surface capturing methodology. Most reported CFD research on wave-in-deck loads consider regular waves only, for instance the Stokes fifth-order waves. They are, however, recognized by designers as approximate approaches since “real world” sea states consist of random irregular waves. In our work, we report a recently developed focused extreme wave maker based on the NewWave theory. This model can better approximate the “real world” conditions, and is more efficient than conventional random wave makers. It is able to efficiently generate targeted waves at a prescribed time and location. The work is implemented and integrated with OpenFOAM, an open source platform that receives more and more attention in a wide range of industrial applications. We will describe the developed numerical method of predicting highly non-linear wave-in-deck loads in the time domain. The model’s capability is firstly demonstrated against 3D model testing experiments on a fixed block with various deck orientations under random waves. A detailed loading analysis is conducted and compared with available numerical and measurement data. It is then applied to an extreme wave loading test on a selected bridge with multiple under-deck girders. The waves are focused extreme irregular waves derived from NewWave theory and JONSWAP spectra.
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Sohn, J. M. "Computational Modelling of Interaction Between CFD And FEA Simulations Under Gas Explosion Loads". In ICSOT Korea 2012 - Developments in fixed and floating offshore structures. RINA, 2012. http://dx.doi.org/10.3940/rina.icsot.2012.15.
Testo completo
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Tralli, Aldo, Arnout C. Bijlsma, Wilbert te Velde e Pieter de Haas. "CFD Study on Free-Surface Influence on Tidal Turbines in Hydraulic Structures". In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41187.
Testo completoAbstract (sommario):
In order to estimate the impact on energy production and environment of tidal turbines placed in or near hydraulic structures like discharge sluices or storm surge barriers, a Computational Fluid Dynamics (CFD) study has been carried out on the relation between (head) loss induced by the turbines and their gross power production. CFD computations have been performed for Tocardo T2 turbines, using STAR-CCM+. Simulations of a single turbine in free flow conditions compare favorably with results of Blade Element Momentum (BEM) computations, in terms of torque and thrust. This BEM method model had been previously validated against both CFD data and field measurements. Then, a series of tests has been performed in a “virtual tow tank”, including the effect of the free surface and the blockage by side and bottom walls. These computations provide a base for a first estimate of the effect of turbines on the discharge capacity of a generic structure. This is considered to be the first step in a more general approach in which ultimately the effect of tidal turbines in the Eastern Scheldt Storm Surge Barrier will be assessed.
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Constantinides, Yiannis, Owen H. Oakley e Samuel Holmes. "CFD High L/D Riser Modeling Study". In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29151.
Testo completoAbstract (sommario):
Fully three dimensional fluid flow simulations are used with a simple structural model to simulate very long risers. This method overcomes many shortcomings of methodologies based on two dimensional flow simulations and can correctly include the effects of three dimensional structures such as strakes, buoyancy modules and catenary riser shapes. The method is benchmarked against laboratory and offshore experiments with model risers of length to diameter ratios up to 4,000. RMS values of vortex induced vibration motions are shown to be in good agreement with measurements. The resources needed to model ultra deep water drilling and production risers are estimated based on current computer technology.