Wind waves are highly complex, random phenomena. One way to describe the irregular nature of the sea surface is the use of wave energy spectrum. Spectral information for wind waves in the Black Sea is extremely limited. Knowledge on spectral characteristics of wind waves would contribute to scientific, engineering and operational coastal and marine activities in the Black Sea. The aim of the present thesis is to investigate characteristics of wind wave spectra for the Eastern Black Sea. This would allow detailed understanding of the nature of the waves occurring in this enclosed basin. Long-term wave measurements obtained by directional buoys deployed offshore at Sinop, Hopa and Gelendzhik were utilized as the three sets of wave data. Records were analyzed to identify them as uni-modal or multi-modal spectra, and occurrences of spectral peaks were computed. Single peaked spectra were studied as belonging to fully arisen or developing sea states. Model parameters of JONSWAP and PM spectra were estimated for the observed spectra by using a least square error method. The records of developing seas were further analyzed to select the ones belonging to stable wind conditions. Fetch dependencies of non-dimensional spectral variables, mean parameters of JONSWAP model spectrum and the envelop of dimensionless spectra were investigated for this data sub-set.

Les échanges de chaleur et de quantité de mouvement à l'interface-océan atmosphère jouent un rôle majeur dans la formation et la dynamique des masses d'air et d'eau. Malgré des décennies de recherche, nous avons encore besoin d'améliorer nos connaissances sur ces échanges, et plus spécifiquement nos connaissances sur les flux turbulents, qui sont des variables clés dans les modèles météorologiques et de climat. Dans ces modèles, les processus turbulents sont des processus sous-maille, non-résolus explicitement, ainsi les flux turbulents doivent être modélisés, au travers de paramétrisations, qui sont pour la plupart réalisées à partir de la théorie des similitudes de Monin-Obukhov [1954]. Cependant, d'une part, l'utilisation d'un modèle implique que les coefficients doivent être ajustés. D'autre part, le modèle lui-même peut demander des améliorations. Malheureusement, l'obtention d'estimations de flux avec une bonne précision est un gros défi, à cause des effets intrusifs de la plate-forme sur la mesure, de la précision limité des instruments et des capacités d'échantillonnages propres de chaque instrument.Notre étude porte sur l'estimation des flux turbulents en mer à partir de mesures réalisées avec la nouvelle plate-forme OCARINA (trimaran autonome) lors des campagnes STRASSE 2012 et AMOP 2014. Nous analysons les caractéristiques de la turbulence dans la couche limite de surface, nous estimons les flux turbulents par différentes méthodes, et nous comparons les valeurs des flux en fonction des conditions environnementales, en prenant en compte l'état de mer. / Exchanges of heat and momentum at the air-sea interface play a major role in the formation and the dynamics of water and air masses. In spite of decades of research, we still need to improve our knowledge of these exchanges, and more specifically our knowledge of turbulent fluxes, which are key variables in meteorological and climate models. In these models, sub-grid turbulent processes, thus turbulent fluxes also have to be modeled, which is mostly done with the Monin-Obukhov (1954, MOS hereafter) similarity theory. However, on the one hand, the use of a model implies that coefficients have to be adjusted. On the other hand, the model itself may require improvements. Unfortunately, obtaining flux estimates that have a good accuracy is a challenging effort, because of the intrusive effect of the platform, the limited accuracy the instruments, and because the instruments have their own sampling volume.Our study focuses on the estimation of turbulent fluxes at sea from measurements made with the new OCARINA platform (autonomous trimaran) during two campaigns : STRASSE 2012 and AMOP 2014. We analyze the characteristics of turbulence in the surface boundary layer, we estimate the turbulent fluxes by different methods, and compare the values of fluxes depending on environmental conditions, taking into account the sea state.

A series of laboratory experiments were conducted at three fetches of 4.8, 8.8 and 12.4 m, and at six wind speeds ranging from 4.1 to 9.6 m/s at each fetch in a wind-wave-current research facility. In addition, five surfactant-influenced experiments were conducted at concentrations ranging from 0.1 to 5.0 ppm at a wind speed of 7.9 m/s and a fetch of 4.8 m. The goals were to examine the momentum transfer and to characterize the turbulent flow structure beneath wind waves, and to investigate the relationship between wind waves and the gas transfer rate at the air-water interface. Digital particle image velocimetry (DPIV) was used to measure two-dimensional instantaneous velocity fields beneath the wind waves. The friction velocities and roughness lengths of the coupled boundary layers were used to characterize the flow regime and momentum transfer. The air-side flows were found to be aerodynamically rough and the water-side flows were found to be in transition and then become hydrodynamically smooth as wind speed increased. Airflow separation from the crests of breaking waves may be responsible for making the air-side boundary layer rougher and water-side boundary layer smoother. Momentum transfer was studied by examining the partitioning of the wind stress into the viscous tangential stress and wave-induced stress. It was found that the wave steepness was the most important wind-wave property that controls the momentum transfer in the coupled boundary layers. Two distinct layers were observed in the near-surface turbulence in the presence of a surfactant and three layers in clean water. In the surfactant-influenced experiments, the energy dissipation rate decayed as zeta^(-0.3) in the upper layer and in the lower layer energy dissipation rate decayed as zeta^(-1.0) similar to a wall-layer. For clean experiments, the energy dissipation rate could be scaled using the depth, friction velocity, wave height and phase speed as proposed by Terray et al. (1996) provided that layer based friction velocities were used. In the upper layer, the near-surface turbulence was dominated by wave-induced motions and the dissipation rates decayed as zeta^(-0.2) at all fetches. Below this in the transition layer turbulence was generated by both wave-induced motions and shear currents and the dissipation rate decayed as zeta^(-2.0) at a fetch of 4.8 m. However, at fetches of 8.8 and 12.4 m, the dissipation rate decayed at two different rates; as zeta^(-2.0) in the upper region and as zeta^(-4.0) in the lower region. In the third layer, the dissipation rate decayed as zeta^(-1.0) similar to a wall-layer at a fetch of 4.8 m. Four empirical relationships commonly used to predict the gas transfer rate were evaluated using laboratory measurements. The gas transfer rate was found to correlate most closely with the total mean square wave slope and varied linearly with this parameter. The three other parameterizations using wind speed, wind friction velocity and energy dissipation did not correlate as well. / Water Resources Engineering

No description available.

学位授与大学：京都大学 ; 取得学位: 博士(工学) ; 学位授与年月日: 2007-09-25 ; 学位の種類: 新制・課程博士 ; 学位記番号: 工博第2844号 ; 請求記号: 新制/工/1418 ; 整理番号: 25529 / An atmosphere-ocean coupled model was developed based on a preexisting non-hydrostatic mesoscale atmosphere model (MM5) and non-hydrostatic ocean circulation model (MITgcm). This model together with a pre-established wind-wave-currents coupled model was applied to a number of regional environmental issue and disaster events to reproduce the present status and past situations and to help our understanding of the physical processes of such problems in terms of atmosphere-ocean interactions including the sea surface waves in the interface between air and sea. The disaster events and environmental issue studied in this thesis are follows. 1) Storm surge induced by Hurricane Katrina in the Gulf coast of USA in 2005. 2) Extreme high waves at Hara coast, Suruga Bay in Japan caused by the super-Typhoon TIP in 1979. 3) Positive and negative feedbacks in typhoon-ocean interaction in case of Typhoon ETAU in 2003. 4) Thermal water circulation in a dam-made lake (Yachiyo Lake) in Hiroshima, Japan concerning on the hydrodynamics in the lake. 5) Reanalysis of the past 47 storms that caused disasters in West Kyushu, Japan. 6) Wave overtopping simulation over through the submerged offshore breakwater and enhance seawall. The Regional Environment and Disaster Prevention Simulator is proposed and constructed based on the regional atmosphere-ocean coupled model in this thesis of which the objective was improvement of the numerical assessment method to disaster events and environment problems by introducing he coupling effects between different systems. / Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13373号 / 工博第2844号 / 新制||工||1418(附属図書館) / 25529 / UT51-2007-Q774 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 関口 秀雄, 教授 間瀬 肇, 教授 中北 英一 / 学位規則第4条第1項該当

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-11Bitstream added on 2014-06-13T20:50:43Z : No. of bitstreams: 1 morais_vs_me_ilha.pdf: 9848157 bytes, checksum: 187eadcaad3e9775d2aa107935283406 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho dá continuidade e aperfeiçoa um modelo automatizado para estimativa de altura de ondas geradas em lagos de barragens, a partir dos dados característicos de vento. Infere sobre a climatologia dos ventos, a fim de determinar as maiores alturas de ondas e identificar pontos críticos, tanto para a segurança à navegação, quanto para as margens do reservatório. Lagos de barragens, foco desta dissertação são, em sua maioria, dotados de vegetação aquática. Dentro dessa temática, uma busca por modelos capazes de qualificar e quantificar o quão as ondas geradas pelo vento reagem ao atravessar esses obstáculos naturais em termos de oscilação das plantas, presentes nas margens, foi também discutida. Para os propósitos aqui expostos, um aplicativo computacional foi utilizado para a previsão de ondas e estruturado de maneira que pudesse fornecer resultados gráficos de forma automatizada com maior precisão e no menor tempo possível. O software, fruto do desenvolvimento dos estudos da equipe de pesquisa e mais recentemente aprimorado no presente trabalho, batizado de OndisaCAD, integra-se dentro de ambientes CADs, precisamente no AutoCAD da Autodesk, possibilitando, assim, a geração de ótimas interfaces e resultados gráficos. No que tange à dissipação de energia através da vegetação existente nos lagos e suas margens, o aspecto dinâmico associado à própria movimentação da vegetação foi comparado ao comportamento do movimento de vigas engastadas em sua parte inferior, o que permitiu prescrever a movimentação dos organismos vivos (plantas) frente a uma excitação provocada pela passagem de onda / This work continues and perfects an automated model for estimating the height of waves generated in lakes dams, entering the characteristic data of the wind. It follows on the climatology of the winds to determine the largest wave heights and identify critical points, for the safety of navigation and margin of the reservoir. Lakes dams, focus of this dissertation are mostly equipped with aquatic vegetation. Inside this subject, a search for models able to qualify and quantify how the waves generated by winds respond to cross these natural barriers in terms of oscillation of plants, present on the margin, was also discussed. For the purposes set out here, a software was used for predicting waves and structured so that could provide automated graphics results with more accurately and with a shortest possible time. The software, due to the development of studies of the research team and more recently extended in the present work, called OndisaCAD, works within CADs environments, specifically in AutoCAD of Autodesk's, allowing the generation of great interfaces and graphical results. With respect to the dissipating energy through the vegetation in the lakes and their margins, the dynamic aspect associated with their movement of the vegetation was compared to the behavior of the movement of beams embedded in its bottom, which allowed to prescribe the movement of living organisms (plants) front of an excitement caused by the passage of a wave

Orientador: Geraldo de Freitas Maciel / Banca: Carlos Roberto Minussi / Banca: Luiz Edival Souza / Resumo: Este trabalho dá continuidade e aperfeiçoa um modelo automatizado para estimativa de altura de ondas geradas em lagos de barragens, a partir dos dados característicos de vento. Infere sobre a climatologia dos ventos, a fim de determinar as maiores alturas de ondas e identificar pontos críticos, tanto para a segurança à navegação, quanto para as margens do reservatório. Lagos de barragens, foco desta dissertação são, em sua maioria, dotados de vegetação aquática. Dentro dessa temática, uma busca por modelos capazes de qualificar e quantificar o quão as ondas geradas pelo vento reagem ao atravessar esses obstáculos naturais em termos de oscilação das plantas, presentes nas margens, foi também discutida. Para os propósitos aqui expostos, um aplicativo computacional foi utilizado para a previsão de ondas e estruturado de maneira que pudesse fornecer resultados gráficos de forma automatizada com maior precisão e no menor tempo possível. O software, fruto do desenvolvimento dos estudos da equipe de pesquisa e mais recentemente aprimorado no presente trabalho, batizado de OndisaCAD, integra-se dentro de ambientes CADs, precisamente no AutoCAD da Autodesk, possibilitando, assim, a geração de ótimas interfaces e resultados gráficos. No que tange à dissipação de energia através da vegetação existente nos lagos e suas margens, o aspecto dinâmico associado à própria movimentação da vegetação foi comparado ao comportamento do movimento de vigas engastadas em sua parte inferior, o que permitiu prescrever a movimentação dos organismos vivos (plantas) frente a uma excitação provocada pela passagem de onda / Abstract: This work continues and perfects an automated model for estimating the height of waves generated in lakes dams, entering the characteristic data of the wind. It follows on the climatology of the winds to determine the largest wave heights and identify critical points, for the safety of navigation and margin of the reservoir. Lakes dams, focus of this dissertation are mostly equipped with aquatic vegetation. Inside this subject, a search for models able to qualify and quantify how the waves generated by winds respond to cross these natural barriers in terms of oscillation of plants, present on the margin, was also discussed. For the purposes set out here, a software was used for predicting waves and structured so that could provide automated graphics results with more accurately and with a shortest possible time. The software, due to the development of studies of the research team and more recently extended in the present work, called OndisaCAD, works within CADs environments, specifically in AutoCAD of Autodesk's, allowing the generation of great interfaces and graphical results. With respect to the dissipating energy through the vegetation in the lakes and their margins, the dynamic aspect associated with their movement of the vegetation was compared to the behavior of the movement of beams embedded in its bottom, which allowed to prescribe the movement of living organisms (plants) front of an excitement caused by the passage of a wave / Mestre

Multiline anchors are a novel way to reduce the cost of arrays of floating offshore wind turbines (FOWTs), but their behavior is not yet fully understood. Through metocean characterization and dynamic simulations, this thesis investigates the effects of wind-wave misalignment on multiline anchor systems. Four coastal U.S. sites are characterized in order to develop IEC design load cases (DLCs) and analyze real-world misaligned conditions. Stonewall Bank, Oregon showed the highest 500-year extreme wave height, at 16.6 m, while Virginia Beach, Virginia showed the highest 500-year wind speed, at 56.8 m/s. Misalignment probability distributions, at all sites, are found to converge towards zero (aligned conditions) and become less variable as wind speed increases. This indicates that high misalignment angles are unlikely at high wind speeds. A simulation parameter study, spanning a range of wave directions, misalignment angles, and DLCs, is run in OpenFAST to explore how misalignment affects multiline anchor loading. The simulated anchor is connected to three IEA 15 MW FOWT models via a taut mooring system. The force on the multiline anchor is calculated by summing the three tension vectors from the mooring lines. The mean direction of this force is found to align closely with the wind; each mean is within 5.5° of the wind direction. Higher misalignment angles cause increases to the amount of directional variation about this mean. The magnitude of the multiline force is also examined. Mean force level is found to be nearly unaffected by misalignment. However, maximum force decreases significantly as misalignment angle increases, dropping as much as 23.3% in extreme conditions. This confirms current anchor design practice, which treats aligned metocean conditions as the peak load an anchor experiences. Standard deviation of multiline force also decreases with misalignment. The operational load case, DLC 1.6, shows a slight trend towards this, but the extreme case, SLC, shows a more pronounced drop of 32.4%. This suggests that anchor cyclic loading analyses could benefit from considering misalignment. Doing so could lead to lower estimates of the cyclic loading amplitudes that anchor designs must withstand, thus leading to smaller, cheaper anchors.

The work deals with mathematical modeling of wind waves on water reservoirs and their effects on different types of slopes. The research work was carried out using a vast array of available literature written on this topic in the Czech Republic and partly abroad. And we also deal with the hydrodynamics problems, creating mathematical and numerical model Further simulations were created in two numerical models. Simulations were created in two programs FLOW-3D and DualSPHysics. Vast variety of situations was created in DualSPHysics program because it seems more appropriate for modeling of this situation. It was created twenty-seven simulations and their results are compared with results coming from valid Czech standard ČSN 75 0255.

Previous research has displayed that multi-source farms provide an opportunity to reduce the cost of energy and improve the energy output quality. This thesis assesses the cost competitiveness of co-located wind-wave farms, specifically floating offshore wind (FLOW) turbines and CorPower’s wave energy converters (WEC). This research was conducted in collaboration with CorPower, a Swedish WEC developer. A cost model is generated, which calculates the levelized cost of energy (LCOE) utilizing a life-cycle cost analysis. The model is developed by combining CorPower’s existing cost model with an agglomeration of FLOW cost models from previous studies. An in depth literature research informs about synergies, which are translated into shared costs within the model. The cost model is applied to a site on the Northern coast of Portugal; the location of a FLOW farm project under development. Including wave energy, improves the annual energy production of the farm by up to 10%. However, the effects on power smoothing are negligible, due to the high seasonal variability of the wave resource and the minimal complementarity of the two energy sources. The LCOE of a 1GW 50% wind - 50% wave farm is 63€/MWh. The high initial investment costs of the wind farm results in the standalone wind LCOE of 73€/MWh. The strong capacity factor of the WECs cause the LCOE to reduce to 55€/MWh, when evaluating a standalone wave farm. In all co-location configurations, savings for FLOW and wave farm developers are exhibited. The highest savings are identified for small wind/wave arrays co-located in large farms. This results in an LCOE reduction of up to 4.5% for both wind and wave farm developers. The largest relative savings are found in the DEVEX costs and the electrical transmission installation costs. The identified cost calculations and savings are inline with previous studies. The savings are in the lower range compared to other studies, due to the conservative estimations of the degree of shared costs. The cost model provides a tool, that can be continuously updated with the most recent findings of cost inputs and wind-wave synergies, i.e. shared cost opportunities. This thesis’ results reflect how co-locating wind and wave farms can improve the cost-competitiveness of both technologies. Nevertheless, more in depth research is required to comprehend the full potential of co-located wind-wave farms. There is a necessity of collaboration between wind and wave industry members to ensure that the synergies and shared cost-opportunities identified, are fully exploited. / Tidigare forskning har visat att parker med flera källor ger möjlighet att minska energikostnaderna och förbättra energiproduktionens kvalitet. I den här avhandlingen utvärderas kostnadskonkurrenskraften hos samlokaliserade vind- och vågkraftsparker, särskilt flytande havsbaserade vindkraftverk (FLOW) och CorPowers vågenergiomvandlare (WEC). Denna forskning genomfördes i samarbete med CorPower, en svensk WEC-utvecklare. En kostnadsmodell genereras, som beräknar den nivellerade energikostnaden (LCOE) med hjälp av en livscykelkostnadsanalys. Modellen är utvecklad genom att kombinera CorPowers befintliga kostnadsmodell med en agglomeration av FLOW-kostnadsmodeller från tidigare studier. En djupgående litteraturstudie ger information om synergier, som översätts till delade kostnader i modellen. Kostnadsmodellen tillämpas på en plats på Portugals norra kust, där ett FLOW-anläggningsprojekt är under utveckling. Genom att inkludera vågenergi förbättras parkens årliga energiproduktion med upp till 10%. Effekterna på effektutjämningen är dock försumbara, på grund av vågresursens stora säsongsvariationer och de två energikällornas minimala komplementaritet. LCOE för en 1GW 50% vind - 50% vågkraftspark är 63€/MWh. De höga initiala investeringskostnaderna för vindkraftsparken resulterar i en LCOE för fristående vindkraft på 73 €/MWh. Den starka kapacitetsfaktorn för WECs gör att LCOE minskar till 55€/MWh, vid utvärdering av en fristående vågkraftspark. I alla samlokaliseringskonfigurationer uppvisas besparingar för FLOW och vågparksutvecklare. De största besparingarna identifieras för små vind-/vågkraftsparker som samlokaliseras i stora parker. Detta resulterar i en minskning av LCOE med upp till 4,5% för både vind- och vågparksutvecklare. De största relativa besparingarna finns i DEVEX-kostnaderna och installationskostnaderna för elektrisk överföring. De identifierade kostnadsberäkningarna och besparingarna är i linje med tidigare studier. Besparingarna ligger i det lägre intervallet jämfört med andra studier, på grund av de konservativa uppskattningarna av graden av delade kostnader. Kostnadsmodellen är ett verktyg som kontinuerligt kan uppdateras med de senaste rönen om kostnadsingångar och synergier mellan vind och våg, dvs. möjligheter till delade kostnader. Resultaten i denna avhandling visar hur samlokalisering av vind- och vågkraftsparker kan förbättra kostnadskonkurrenskraften för båda teknikerna. Det krävs dock mer djupgående forskning för att förstå den fulla potentialen hossamlokaliserade vind- och vågparker. Det finns ett behov av samarbete mellanvind- och vågkraftsindustrin för att säkerställa att de identifierade synergierna ochgemensamma kostnadsmöjligheterna utnyttjas fullt ut.