Letteratura scientifica selezionata sul tema "Wind-wave flume"
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Articoli di riviste sul tema "Wind-wave flume"
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Oost, W. A. "The wind profile in a wave flume". Journal of Wind Engineering and Industrial Aerodynamics 37, n. 2 (marzo 1991): 113–21. http://dx.doi.org/10.1016/0167-6105(91)90067-7.
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Tsoukala, V. K., e C. I. Moutzouris. "Gas transfer under breaking waves: experiments and an improved vorticity-based model". Annales Geophysicae 26, n. 8 (31 luglio 2008): 2131–42. http://dx.doi.org/10.5194/angeo-26-2131-2008.
Testo completoAbstract (sommario):
Abstract. In the present paper a modified vorticity-based model for gas transfer under breaking waves in the absence of significant wind forcing is presented. A theoretically valid and practically applicable mathematical expression is suggested for the assessment of the oxygen transfer coefficient in the area of wave-breaking. The proposed model is based on the theory of surface renewal that expresses the oxygen transfer coefficient as a function of both the wave vorticity and the Reynolds wave number for breaking waves. Experimental data were collected in wave flumes of various scales: a) small-scale experiments were carried out using both a sloping beach and a rubble-mound breakwater in the wave flume of the Laboratory of Harbor Works, NTUA, Greece; b) large-scale experiments were carried out with a sloping beach in the wind-wave flume of Delft Hydraulics, the Netherlands, and with a three-layer rubble mound breakwater in the Schneideberg Wave Flume of the Franzius Institute, University of Hannover, Germany. The experimental data acquired from both the small- and large-scale experiments were in good agreement with the proposed model. Although the apparent transfer coefficients from the large-scale experiments were lower than those determined from the small-scale experiments, the actual oxygen transfer coefficients, as calculated using a discretized form of the transport equation, are in the same order of magnitude for both the small- and large-scale experiments. The validity of the proposed model is compared to experimental results from other researchers. Although the results are encouraging, additional research is needed, to incorporate the influence of bubble mediated gas exchange, before these results are used for an environmental friendly design of harbor works, or for projects involving waste disposal at sea.
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Wei, Chengxun, Shenghui Li e Haiying Mao. "Development of a Wind–Wave Coherence Function Based on Numerical Studies". Water 16, n. 17 (9 settembre 2024): 2552. http://dx.doi.org/10.3390/w16172552.
Testo completoAbstract (sommario):
The synchronization and intensity of fluctuating wind speeds and wave surfaces in wind–wave joint propagation processes are affected by the coherence of the marine ambient factors of fluctuating wind and random waves. This coherence further affects the precise calculations of wind–wave joint actions on marine structures. Therefore, a wind–wave joint propagation numerical flume was established based on the numerical simulation of random waves and fluctuating wind fields. A series of numerical simulations of wind–wave joint propagations were carried out. Based on the numerical results, the influences and influence laws of factors such as wind speed position height, significant wave height and wave spectrum peak frequency on the wind–wave coherence values were studied. According to the influence characteristics of these factors, a function of wind–wave coherence values for random wind–wave joint propagation was calculated. The coherence function takes frequency as the variable, while parameters include significant wave height, wind speed position height and wave spectrum peak frequency. Through a series of numerical simulation results, data fitting was used to calculate the parameter coefficients of the coherence function. The established random wind–wave coherence function can be described using the wind–wave joint fields of marine structures and the computational analyses of structural wind–wave joint actions.
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Syamsidik, Syamsidik, Benazir Benazir, Nadri Pratama, Arifullah Arifullah, Eldina Fatimah, Nazaruddin Nazaruddin, Tarmizi Tarmizi, Ibrahim Ibrahim e Ikramullah Zein. "A New Multi-Purposes Flume Experiments Facility: Challenges and Opportunity for Tsunami and Coastal Engineering in Indonesia". International Journal of Disaster Management 6, n. 3 (24 marzo 2024): 345–54. http://dx.doi.org/10.24815/ijdm.v6i3.34568.
Testo completoAbstract (sommario):
Physical modelling for tsunami engineering is rather difficult to conduct due to lack of comprehensive and advanced facilities to do so. Large number of simulations of the tsunami impacts were performed numerically. In early 2023, a new advanced tsunami flume facility has been completed at Tsunami and Disaster Mitigation Research Center (TDMRC) of Universitas Syiah Kuala. This flume has 60 m in length, 2.5 m in width, and 1.7 m in height. The flume is also equipped with a number of wave, pressure, and current sensors, Particle Image Velocimetery (PIV) Camera, and a laser bed profiler. Beside of the tsunami generator, this flume is also capable to generate wind-driven waves (with two large wind turbines), regular and irregular waves, and currents. The flume provides new opportunities as well as challenges for tsunami scientists and engineers in Indonesia to collaborate and to perform novel researches in tsunami mitigation. This article is aimed at elucidating technical challenges and opportunities in performing tsunami physical models with the large tsunami flume. we performed a series numerical models using DualSPHysic. The results show that composite beach slopes inside the flume has succesfully mimic shallow coast effects that later deformed the incoming tsunami waves into breaking, bores, and runup. Challenges were identified in absorbing tsunami waves with more than one incoming wave to the observation area. In the future, this facility will be accessible for scientists and engineers to collaborate in tsunami science and engineering researches.
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Zavadsky, A., D. Liberzon e L. Shemer. "Statistical Analysis of the Spatial Evolution of the Stationary Wind Wave Field". Journal of Physical Oceanography 43, n. 1 (1 gennaio 2013): 65–79. http://dx.doi.org/10.1175/jpo-d-12-0103.1.
Testo completoAbstract (sommario):
Abstract Detailed investigation of wind-generated water waves in a 5-m-long wind wave flume facility is reported. Careful measurements were carried out at a large number of locations along the test section and at numerous airflow rates. The evolution of the wind wave field was investigated using appropriate dimensionless parameters. When possible, quantitative comparison with the results accumulated in field measurements and in larger laboratory facilities was performed. Particular attention was given to the evolution of wave frequency spectra along the tank, distinguishing between the frequency domain around the spectral peak and the high-frequency tail of the spectrum. Notable similarity between the parameters of the evolving wind wave field in the present facility and in field measurements was observed.
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Deng, Sijia, Ming Qin, Dezhi Ning, Lin Lin, Songxiong Wu e Chongwei Zhang. "Numerical and Experimental Investigations on Non-Linear Wave Action on Offshore Wind Turbine Monopile Foundation". Journal of Marine Science and Engineering 11, n. 4 (21 aprile 2023): 883. http://dx.doi.org/10.3390/jmse11040883.
Testo completoAbstract (sommario):
Monopiles are commonly utilized in offshore wind farms but are prone to non-linear wave loads and run-ups, significantly affecting their engineering design. Therefore, it is crucial to pursue a complete understanding of the non-linear wave action on monopile foundations. Both numerical and experimental investigations on the non-linear wave loads and run-ups on an offshore wind turbine monopile foundation are performed in this paper. The experiment is carried out at a scale of 1/30 in a wave flume at the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, in which the wave loads and run-ups along the monopile are measured. Based on the second-order potential flow model and time-domain higher-order boundary element method (HOBEM), the related numerical tests are conducted to study the non-linear effects further. It is found that the present non-linear potential theory is sufficient for the simulation of wave force and run-ups on the monopile in the range of wave slope kA < 0.15 before wave breaking. “W” type distribution of wave run-up along the monopile is found, in which the peak value occurs at the frontward side (i.e., θ =180°) and is the maximum due to full reflection; the two symmetrical minimum amplitudes lie in the zones of (45° ≤ θ ≤ 90°) and (270° ≤ θ ≤ 315°), whose positions shift downward with the increase of wave non-linearity. Energy transfer among the fundamental wave component and higher-order components is also found, which is most apparent on the backward side. Besides, the transverse resonance occurs in the wave flume due to the wavelength being near the flume width, which induces the wave run-up at the backward position larger than that at the frontward position.
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KAWASAKI, Koji, e Masami KIKU. "PROPOSAL OF NUMERICAL WAVE FLUME FOR WAVE OVERTOPPING ANALYSIS CONSIDERING WIND EXTERNAL FORCE". Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) 67, n. 2 (2011): I_58—I_63. http://dx.doi.org/10.2208/jscejoe.67.i_58.
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Kiku, Masami, e Koji Kawasaki. "PROPOSAL OF NUMERICAL WAVE FLUME FOR WAVE OVERTOPPING COMPUTATION CONSIDERING WIND EXTERNAL FORCE". Coastal Engineering Proceedings 1, n. 34 (30 ottobre 2014): 8. http://dx.doi.org/10.9753/icce.v34.waves.8.
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Kandaurov, Alexander, Daniil Sergeev, Yuliya Troitskaya e Olga Ermakova. "Investigation of the mechanisms of sea spray generation induced by wind-wave interaction in laboratory conditions". EPJ Web of Conferences 213 (2019): 02036. http://dx.doi.org/10.1051/epjconf/201921302036.
Testo completoAbstract (sommario):
The paper presents the results of investigations of the mechanisms of spray of droplets generation within wind wave interaction obtained under laboratory conditions on the High-speed Wind-Wave Flume of the Institute of Applied Physics of the Russian Academy of Sciences. For the research, a multi-angle high-speed video system used together shadow method, including underwater illumination. The results allowed for the classification of mechanismsleading to the formation of droplets. Three main types of phenomena responsible for the generation of the spume droplets near the wave crest were specified: breakage of liquid ligaments, bursting of large submerged bubbles, and bag breakup. The last and less known mechanism claims to be dominant for high wind speeds and it was described in detail.
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Chowdhury, S. De, J. G. Zhou, L. Qian, D. Causon, C. Mingham, T. Pullen, K. Hu et al. "WIND EFFECTS ON OVERTOPPING DISCHARGE AT COASTAL DEFENCES". Coastal Engineering Proceedings, n. 36v (31 dicembre 2020): 40. http://dx.doi.org/10.9753/icce.v36v.papers.40.
Testo completoAbstract (sommario):
Wind effects on wave overtopping over fully impermeable vertical sea defence is studied in a shallow water flume based on a physical model for the Livermeade defence system. The investigation is mainly focused on impulse type wave interaction with the sea defence, when the overshooting jet is high during overtopping. We are able to identify distinct types of overtopping flows where moderate wind speed is not found to be affecting uniformly in all cases. We try to find explanation of this behaviours by studying the standing waves at the defence and complementary CFD simulations.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/byRz_N9zoXk
Tesi sul tema "Wind-wave flume"
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Bourg, Natacha. "Interactions between boundary currents, fronts and eddies in the Northern Current and the East Australian Current. : Transport dynamics and application to the journey of Physalia spp". Electronic Thesis or Diss., Toulon, 2024. http://www.theses.fr/2024TOUL0001.
Testo completoAbstract (sommario):
Les courants de bords, caractérisés par de fortes vitesses et de nombreuses interactions dynamiques avec les marges continentales, sont les principaux moteurs de la variabilité océanique dans les régions côtières qu’ils traversent. La première partie de cette thèse se concentre sur les observations Radar Haute-Fréquence du Courant Nord dans la Méditerranée Nord-Occidentale et du courant est-australien dans l’océan Pacifique Sud. Nous étudions la variabilité saisonnière et interannuelle du courant et le développement de tourbillons de (sous) méso-échelle dans le système du Courant Nord. Concernant le courant est-Australien, nous examinons plus particulièrement sa dynamique de séparation, ses caractéristiques frontales et son impact sur la concentration de chlorophylle-a en surface.Les courants de bord, de par leur grande étendue et leur position le long du plateau continental,sont importants car ils agissent à la fois comme des barrières et des courroies de transport de matière passive. La deuxième partie se concentre sur Physalia spp., un organisme urticant pseudo-passif flottant à la surface de l’océan qui atteint régulièrement les côtes australiennes. Nous avons pu estimer l’impact relatif des variables météo-marines sur leur échouage. A partir d’expériences en laboratoire, nous établissons une paramétrisation de la dérive de maquettes 3D de Physalia spp. induite par le vent. Ce résultat,intégré dans une modélisation de suivi lagrangien selon des scénarios typiques du courant est-Australien nous permet de déterminer l’influence cumulée du vent et du courant sur les trajectoires des Physalia spp. Les résultats présentés dans cette thèse contribuent à la connaissance de deux courants de bord, caractérisés par des échelles et des modes de variabilité différents, et illustrent leur rôle dans le transport de matière passive à travers l’étude de la dérive de Physalia sppBoundary currents, characterized by strong velocities and dynamic interactions with continental margins are the main drivers of ocean variability in the adjacent coastal regions. The first part of the thesis focuses on High-Frequency RADAR observations of the Northern Current in the North Western Mediterranean Sea and of the East Australian Current in the South Pacific Ocean. In the Northern Current system, we investigate the seasonal and inter-annual variability of the current and the occurrence of (sub) mesoscale eddies, while we focus on the study of the separation dynamics of the East Australian Current, its frontal characteristics and overall impact on surface chlorophyll-a concentration. Boundary currents, by their spatial extent and position along the continental shelf, are important in acting both as barriers and conveyers of transport of passive matter. The second part of the thesis focuses on Physalia spp., a pseudo-passive stinging organism floating at the ocean surface which regularly reaches Australian shores. We are able to estimate the relative impact of atmospheric and oceanic variables on Physalia spp. beaching. From laboratory experiments, we establish a parametrization of the wind-induced drift of 3D-printed replicas of Physalia spp. This result is then incorporated into a Lagrangian tracking model based on the most recurrent East Australian Current separation scenarios to assess the combined effects of winds and currents on the pathways of Physalia spp. The results presented in this thesis contribute to the knowledge of two boundary currrents characterized by different scales and modes of variability, giving insights in their role in transport of passive material through the study of Physalia spp journey
Capitoli di libri sul tema "Wind-wave flume"
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Gao, Ang, Xiufeng Wu, Shiqiang Wu, Hongpeng Li, Jiangyu Dai e Fangfang Wang. "Study on Wind Waves Similarity and Wind Waves Spectrum Characteristics in Limited Waters". In Lecture Notes in Civil Engineering, 1220–35. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6138-0_107.
Testo completoAbstract (sommario):
AbstractWind waves is an important factor affecting navigation safety and water environment in limited waters such as lakes and bays. Wind wave spectrum represents the frequency domain features of wind waves and has always been the focus of research. Based on the field observation and flume experimental method, the system analysis of similarity of two kinds of situations, discussed nonlinear response of the relationship of the spectral shape parameter of balance field α, β and wind waves basic frequency between factors like wind speed, wind blowing fetch and water depth. By means of wind tunnel flume and prototype observation data of nonlinear regression analysis, The relation formulas of wind wave frequency prediction considering the comprehensive influence of wind speed, wind blowing fetch and water depth is established. Relevant research is of great significance for revealing the evolution characteristics of wind waves in limited waters and guiding navigation safety and water environment management.
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Peirson, W. L. "Observational Studies of the Surface Velocity Phase Structure of Microscale Breaking Wind Waves". In Wind-over-Wave Couplings, 203–10. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198501923.003.0021.
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Abstract The phase structure of the surface velocity associated with wind-driven microscale breaking waves has been measured in a laboratory wind-wave flume using Particle Image Velocimetry (PIV) techniques. Contrary to previous studies, it is found that, on average, the surface flow at the crest does not contribute directly to the spilling regions of these small waves. In general, the net surface transport relative to the wave form is rear ward along the entire wave surface except in the immediate vicinity of the spilling region itself. Such findings have important implications in the de termination of appropriate surface boundary conditions for models of air flow over waves and theoretical and physical investigations of air-sea mass transfer.
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Ely, Mark C., e Amy E. Van Deuren. "Flute". In Wind Talk for Woodwinds, 81–187. Oxford University PressNew York, NY, 2009. http://dx.doi.org/10.1093/oso/9780195329186.003.0002.
Testo completoAbstract (sommario):
Abstract Acoustical Properties: The acoustical and physical tonal characteristics of an instrument that affect its sound quality. Although the head joint is slightly conical, the flute is essentially a cylindrical tube that is open on both ends. Sound is produced when air is blown against the sharp edge of the embouchure hole, causing the air column inside the instrument to vibrate. Players can produce different octaves or partials by changing air speed and direction. Harmonically speaking, the flute produces the purest tone of any wind instrument; that is, the sound wave is almost sinusoidal at times. The flute’s tone quality blends well with other instruments; however, it is also easily masked by the complex tones (i.e., tones that contain many partials) produced by other wind instruments. Modern flutes are most commonly made of nickel silver (also called German silver, an alloy consisting of copper, zinc, and nickel), silver plate, or solid silver. Many professional flute makers use a wide variety of metal and wood in their flutes, including yellow gold, rose gold, platinum, and grenadilla wood. These materials offer players the option of choosing an instrument that inherently produces a particular quality of sound.
Atti di convegni sul tema "Wind-wave flume"
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Sidqi Fidari, Jadfan. "WIND-WAVE INTERACTION MODELING AND HYDRAULIC PHENOMENON USING FLUME MODEL". In International conference on Innovation and Technology. JOURNAL OF INNOVATION AND APPLIED TECHNOLOGY, 2021. http://dx.doi.org/10.21776/ub.jiat.2021.se.01.010.
Testo completoAbstract (sommario):
The phenomenon of waves caused by wind is a very common problem in climate-related fields. Research on the wind-wave relationship has been carried out since 1968 by Wu. This research was conducted to determine the effect of wind and wind interaction on water using a flume model but with wind flow approach for low regimes. In low-flow fluid regimes, the potential for wind waves to cause damage needs to be investigated, this is because wind-wave interactions can cause sediment dispersion, sediment mixing cycles in the water column, and sediment compaction. The approach methodology used to determine the effect of wind variables and modeling that occurs in the flume model uses the interaction approach of wind waves and their interactions with the water profile while seeing the results of hydraulic phenomena caused by these interactions using a numerical modeling approach. This study will provide an overview of the condition of the hydraulic phenomenon during the interaction of wind waves and show how the interaction of wind and water occurs on the surface of the water, as well as the potential for large enough hazards for water resource management and disasters in the surrounding community if there is a high risk or threat. what happens if these conditions do not meet climatological safety standards in Indonesia.
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Toffoli, A., D. Proment, H. Salman, J. Monbaliu, E. Stramignoni, R. Forza, M. Manfrin e M. Onorato. "Rogue Waves in Wind Seas: An Experimental Model in an Annular Wind-Wave Flume". In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61156.
Testo completoAbstract (sommario):
The probability of occurrence of rogue waves in wind-generated fields is investigated experimentally in an annular wind-wave flume. Unlike many experiments on rogue waves, where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. The peculiar geometry of the flume makes waves propagating circularly in an unlimited-fetch condition. Water surface elevation was measured at specific cross-sections under the effect of different wind speeds to monitor the temporal evolution of the wave field. Results show that the kurtosis of the surface elevation, the fourth order moment of the probability density function and a measure of the percentage of extremes in a wave record, gradually increases in time with the evolution of the wave field. Deviations from Normal statistics are observed to be a function of wind speed. The maximum departure from Normality resembled the one induced by quasi-resonant wave-wave interactions and it is observed at the final stage of wave growth and immediately before reaching the fully development regime.
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Liang, Bingchen, Ying Liu e Lili Yang. "Numerical Experiments Analysis of Wave-Induced Vertical Mixing’s Effects on Sea Surface Wind-Induced Momentum Transfer". In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20739.
Testo completoAbstract (sommario):
A hydrodynamic sediment coupled model COHERENS-SED, which has been developed by the present authors through introducing wave-enhanced bottom stress, wave dependent surface drag coefficient, wave-induced surface mixing, SWAN, damping function of sediment on turbulence and sediment model to COHERENS, is modified to account for wave-induced vertical mixing. One equation k–ε turbulence model is taken into account in calculating vertical viscosity coefficient. COHERENS-SED consists of sediment model SED, current model COHERENS and wave generation model SWAN. The model can also calculate one-dimensional, two-dimensional and three-dimensional current separately. One-dimensional model and three-dimensional model are adoptted to study the wave-induced vertical mixing’s effects. The horizontal current velocity profiles given by the model, with same input conditions as what to get analytical results, are in nice agreement with analytical velocity profiles. Therefore the model can be reliable to identify wave-induced vertical mixing’s effects on horizontal velocity profiles and momentum transferring. Two group numerical experiments are built based on 130m water depth and 20m water depth for the one-dimensional model. Results show that higher wave height can generate larger vertical eddy viscosity and lower horizontal velocity generally. In order to find out such effects on fresh water flume momentum transfer towards down in vertical section of estuary, Yellow River delta is chosen to study the effects of wave-induced vertical diffusion on sediment vertical mixing and the Yellow River estuary vertical cross-section is chosen to study fresh water disperse range in vertical section. The results of fresh water shows that wave-induced vertical mixing increases the momentum of fresh water transferring ability towards down to seabed. So fresh water flume length is compressed obviously.
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Campos, Alexis, Climent Molins, Xavier Gironella, Pau Trubat e Daniel Alarcón. "Experimental RAO’s Analysis of a Monolithic Concrete SPAR Structure for Offshore Floating Wind Turbines". In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41891.
Testo completoAbstract (sommario):
Nowadays the offshore wind energy market is clearly oriented to be extended around the world. Bottom fixed solutions for supporting offshore wind turbines are useful in shallow waters which are available in a limited extent unless a continental shelf exists. Considering the Oil & Gas background knowledge, move from bottom fixed solutions to floating solutions is not a technical challenge, but the cost of each structure in terms of industry profit is currently the main issue for its commercial implementation. That point has induced huge research efforts on the topic. Recently, a new concept consisting of a monolithic concrete SPAR platform was experimentally and numerically studied in the framework of the AFOSP KIC-InnoEnergy project (Alternative Floating Platform Designs for Offshore Wind Towers using Low Cost Materials) [1] [2]. The studies comprised a set of hydrodynamic tests performed in the CIEM wave flume facility at UPC, with a 1:100 scaled model assuming Froude similitude. The whole test campaign includes free decay tests, RAO’s determination, regular and irregular waves with and without wind mean force. For the determination of the platform RAO’s, a set of 21 regular waves trains with periods ranging from 0.8s up to 4.8s were applied. The 6 DOF motions of the platform were measured with an infrared stereoscopic vision system. In this paper, a summary of pitch and heave RAO’s tests will be presented with the main objective to calibrate and validate the accuracy of the Morison-based numerical model for floating wind turbine platforms developed at the Universitat Politècnica de Catalunya. Because the wave flume spatial constraints, both Airy and Stokes wave theories are necessary to reproduce the correct wave kinematics. The numerical model includes both theories and a comparison between them has been done, checking the validity range of each one. The simulations revealed a reasonable good agreement with the experimental results, as well with the computed RAO’s in commercial software.
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Lin, Yu-Hsien, Jing-Fu Chen e Po-Ying Lu. "Numerical Simulation of Wave Run-Ups due to Nonlinear Interaction Between Stokes Waves and Offshore Wind Turbines". In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54013.
Testo completoAbstract (sommario):
This paper conducts a RANS solver with k-ε turbulent closure to simulate hydrodynamics of wave run-ups of three types of wind turbine foundations, including monopile, gravity-based and tripod support structures. In this study, a semi-empirical formula is developed and calibrated based on velocity stagnation head theory by means of a CFD model, FLUENT. The numerical results are validated by the experimental data, which were implemented in the Large Wave Flume (GWK) of the Coastal Research Centre (FZK) in Hannover and published by Mo et al. (2007) [1]. It is indicated that the difference of normalized run-up envelopes among these wind turbine foundations is smaller for higher wave steepness than those for lower wave steepness. It is also obvious that the tendency of maximum run-up heights is considerably correlated with higher nonlinearity, whereas an opposite trend is obtained for minimum run-up envelops. Eventually, a calibrated run-up parameter is obtained by the present numerical simulation and found that the value becomes smaller with respect to higher nonlinearity and run-up heights.
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Chakkurunni Palliyalil, Vipin, Panneer Selvam Rajamanickam, Mayilvahanan Alagan Chella e Vijaya Kumar Govindasamy. "Experimental Investigations of Breaking Wave Impact Forces on a Monopile Substructure for Offshore Wind Turbines Under Regular Breaking Waves". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71227.
Testo completoAbstract (sommario):
The main objective of the paper is to investigate wave impact forces from breaking waves on a monopile substructure for offshore wind turbine in shallow waters. This study examines the load assessment parameters relevant for breaking wave forces on a vertical circular cylinder subjected to breaking waves. Experiments are conducted in a shallow water flume and the wave generation is based on piston type wave maker. The experiments are performed with a vertical circular cylinder with diameter, D = 0.20m which represents a monopile substructure for offshore wind turbines with regular waves of frequencies around 0.8Hz. The experimental setup consists of a 1/10 slope followed by a horizontal bed portion with a water depth of 0.8m. Plunging breaking waves are generated and free surface elevations are measured at different locations along the wave tank from wave paddle to the cylinder in order to find the breaking characteristics. Wave impact pressures are measured on the cylinder at eight different vertical positions along the height of the cylinder under breaking waves for different environmental conditions. The wave impact pressures and wave surface elevations in the vicinity of the cylinder during the impact for three different wave conditions are presented and discussed.
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Bhirawa, Tunggul, Kevin, Jung H. Lee e Jason P. Monty. "Laboratory Study on the Turbulent Boundary Layers Over Wind-Waves Roughness". In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77819.
Testo completoAbstract (sommario):
A laboratory study of turbulent boundary layers over wind-generated waves using Particle Image Velocimetry (PIV) in a wind-wave flume at the University of Melbourne is presented. The experiments are taken at two different wind speeds of 5.5 and 8.5 m/s at a fetch length of 3.5 m. Two types of multi-camera measurement are specifically tailored to capture the flow behaviours. The first is a measurement with high spatial resolution, with aims of characterizing the mean velocity, surface drag and Reynolds stresses over the non-stationary surface. The second type is a large field-of-view measurement, designed to capture the large-scale turbulent motions which are directly associated with the surface-wave topography. Although the turbulent flow is developed over a non-stationary surface (i.e. wind-generated waves), it embodies similarities in both integral parameters and Reynolds stress behaviours to the turbulent flows over stationary rough surfaces. This observation could open a possibility to develop an important turbulence model as well as drag prediction over wind-generated waves, which could be closely related to stationary rough-wall boundary layers.
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Han, Mengmeng, Chien Ming Wang e Wenhui Duan. "Wave Response of a Novel Breakwater Concept With Oscillating Water Columns". In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95860.
Testo completoAbstract (sommario):
Abstract A novel concept of a mega floating breakwater-windbreak is proposed for reducing both wave height and wind speed on its leeward side. L-shaped internal channels are installed inside the breakwater hull that surface from the floating breakwater as tubes that function like “trees” to break the wind. The channel openings are on the vertical walls at the upstream side of the breakwater, so that water is allowed to oscillate inside the channels and create extra viscous damping. Numerical studies using both linear boundary element method and CFD were carried out to determine the wave transmissibility and wave force on the breakwater with and without the internal channels. The wave condition in the Gold Coast, Australia was selected as an environmental input. Operating wave condition and extreme wave condition were separately investigated. Scaled dimensions were used to study the breakwater behavior in a wave flume. The results show that when water oscillates inside the channels, the transmitted wave height and lateral wave force acting on the breakwater will be reduced. In addition, since the viscous effect influences waves of all lengths, the internal channels improves the breakwater performance in blocking long waves.
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Joy, Chinsu Mereena, Anitha Joseph e Lalu Mangal. "Experimental Investigation on the Dynamic Response of a Three Legged Articulated Type Offshore Wind Tower". In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54635.
Testo completoAbstract (sommario):
Demand for renewable energy sources is rapidly increasing since they are able to replace depleting fossil fuels and their capacity to act as a carbon neutral energy source. A substantial amount of such clean, renewable and reliable energy potential exists in offshore winds. The major engineering challenge in establishing an offshore wind energy facility is the design of a reliable and financially viable offshore support for the wind turbine tower. An economically feasible support for an offshore wind turbine is a compliant platform since it moves with wave forces and offer less resistance to them. Amongst the several compliant type offshore structures, articulated type is an innovative one. It is flexibly linked to the seafloor and can move along with the waves and restoring is achieved by large buoyancy force. This study focuses on the experimental investigations on the dynamic response of a three-legged articulated structure supporting a 5MW wind turbine. The experimental investigations are done on a 1: 60 scaled model in a 4m wide wave flume at the Department of Ocean Engineering, Indian Institute of Technology, Madras. The tests were conducted for regular waves of various wave periods and wave heights and for various orientations of the platform. The dynamic responses are presented in the form of Response Amplitude Operators (RAO). The study results revealed that the proposed articulated structure is technically feasible in supporting an offshore wind turbine because the natural frequencies are away from ocean wave frequencies and the RAOs obtained are relatively small.
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Wu, Minghao, Jonas Arnout, Josep Molina Ruiz, Carlos Arboleda Chavez, Vasiliki Stratigaki e Peter Troch. "Evaluation of Uncertainty of Damage Results in Experimental Modelling of Monopile Foundation Scour Protection". In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95793.
Testo completoAbstract (sommario):
Abstract The waves and currents acting near a monopile foundation will potentially lead to scour, which may affect the stability of the wind turbine. The design of scour protection against the seabed lowering around a wind turbine monopile foundation is an important issue for wind energy industries. Many laboratory tests have been carried out to investigate the relationship between the hydrodynamic conditions and the monopile foundation scour protection layer damage, and various design criteria have been proposed. However, the experimental uncertainty of the underlying test results has not been discussed in detail. In the present research, small scale wave flume experiments of a 5m diameter monopile foundation scour protection under waves combined with currents in shallow water are described. Two groups of repetitive experiments are completed under the same wave and current conditions. The erosion development of the scour protection armor layer is measured by using a laser profiler and is evaluated based on three dimensional damage numbers. Together with visualization of the damage pattern, the damage analysis discusses the erosion in different subareas and the variances of the subarea damage number. The analysis of the uncertainty of the erosion results based on two sets of repetitive tests has been carried out. Using the uncertainty analysis methodology stated in ISO GUM standard: JCGM 100-2008, the Type A uncertainty, calibration uncertainty and combined uncertainty of the experiment are evaluated separately. The Type A uncertainty gives an overall uncertainty level and it shows that higher uncertainty occurs in the regions where stronger vortices exist. The combined uncertainty is analyzed based on scour protection dynamic stability design formula. Analysis result shows that the uncertainty due to modelling is a major source of the total uncertainty. The study gives a preliminary result of uncertainty level in wave flume test of monopile scour protection and provides a reference for future experimental research.