Articles de revues : « Wave energy absorption »

1

Gao, Hong, et Zhiheng Wang. « Hydrodynamic Response Analysis and Wave Energy Absorption of Wave Energy Converters in Regular Waves ». Marine Technology Society Journal 51, n^o 1 (1 janvier 2017) : 64–74. http://dx.doi.org/10.4031/mtsj.51.1.7.

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AbstractThe hydrodynamic response and the energy capture analysis of wave energy converters (WECs) with three degrees of freedom are conducted using a frequency domain approach. Considering the coupled hydrodynamic coefficients between surge and pitch, motion responses in surge, heave, and pitch are solved for the WECs. The power take-off (PTO) damping is taken as a linear function of the velocity. The power absorption and the absorption efficiency in surge, heave, and pitch are analyzed and compared. The effects of the geometry, diameter, draft, center of gravity position, and PTO damping on the hydrodynamic response, the power absorption, and the absorption efficiency of WECs are investigated. A cylinder, a halfsphere cylinder, and a cone cylinder are examined. From the total power absorption and the efficiency, the cone is the optimum geometry. For the cylinder, the power absorption in heave increases obviously with the increase of the diameter or the draft in a certain range. For the cone, the effect of diameter and draft on the power absorption in heave is relatively small. The cone has a better ability to absorb power in surge and pitch with an intermediate draft and diameter, and the power absorption peak in pitch decreases as Zg increases. The center of gravity position has no effect on the hydrodynamic response and the power absorption in heave. For a cylinder, the optimal PTO damping in heave is higher than that in pitch and surge. The optimum frequency in heave is lower than that in pitch and surge.

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Nakamura, Shoichi, et Shigeru Naito. « IV-3 Wave energy absorption of irregular waves ». Ocean Engineering 12, n^o 6 (janvier 1985) : 577. http://dx.doi.org/10.1016/0029-8018(85)90050-2.

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Verao Fernandez, Gael, Vasiliki Stratigaki, Panagiotis Vasarmidis, Philip Balitsky et Peter Troch. « Wake Effect Assessment in Long- and Short-Crested Seas of Heaving-Point Absorber and Oscillating Wave Surge WEC Arrays ». Water 11, n^o 6 (29 mai 2019) : 1126. http://dx.doi.org/10.3390/w11061126.

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In the recent years, the potential impact of wave energy converter (WEC) arrays on the surrounding wave field has been studied using both phase-averaging and phase-resolving wave propagation models. Obtaining understanding of this impact is important because it may affect other users in the sea or on the coastline. However, in these models a parametrization of the WEC power absorption is often adopted. This may lead to an overestimation or underestimation of the overall WEC array power absorption, and thus to an unrealistic estimation of the potential WEC array impact. WEC array power absorption is a result of energy extraction from the incoming waves, and thus wave height decrease is generally observed downwave at large distances (the so-called “wake” or “far-field” effects). Moreover, the power absorption depends on the mutual interactions between the WECs of an array (the so-called “near field” effects). To deal with the limitations posed by wave propagation models, coupled models of recent years, which are nesting wave-structure interaction solvers into wave propagation models, have been used. Wave-structure interaction solvers can generally provide detailed hydrodynamic information around the WECs and a more realistic representation of wave power absorption. Coupled models have shown a lower WEC array impact in terms of wake effects compared to wave propagation models. However, all studies to date in which coupled models are employed have been performed using idealized long-crested waves. Ocean waves propagate with a certain directional spreading that affects the redistribution of wave energy in the lee of WEC arrays, and thus gaining insight wake effect for irregular short-crested sea states is crucial. In our research, a new methodology is introduced for the assessment of WEC array wake effects for realistic sea states. A coupled model is developed between the wave-structure interaction solver NEMOH and the wave propagation model MILDwave. A parametric study is performed showing a comparison between WEC array wake effects for regular, long-crested irregular, and short-crested irregular waves. For this investigation, a nine heaving-point absorber array is used for which the wave height reduction is found to be up to 8% lower at 1.0 km downwave the WEC array when changing from long-crested to short-crested irregular waves. Also, an oscillating wave surge WEC array is simulated and the overestimation of the wake effects in this case is up to 5%. These differences in wake effects between different wave types indicates the need to consider short-crested irregular waves to avoid overestimating the WEC array potential impacts. The MILDwave-NEMOH coupled model has proven to be a reliable numerical tool, with an efficient computational effort for simulating the wake effects of two different WEC arrays under the action of a range of different sea states.

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Troch, Peter, Charlotte Beels, Julien De Rouck et Griet De Backer. « WAKE EFFECTS BEHIND A FARM OF WAVE ENERGY CONVERTERS FOR IRREGULAR LONG-CRESTED AND SHORT-CRESTED WAVES ». Coastal Engineering Proceedings 1, n^o 32 (1 février 2011) : 53. http://dx.doi.org/10.9753/icce.v32.waves.53.

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The contribution of wave energy to the renewable energy supply is rising. To extract a considerable amount of wave power, Wave Energy Converters (WECs) are arranged in several rows or in a ’farm’. WECs in a farm are interacting (e.g. the presence of other WECs influence the operational behaviour of a single WEC) and the overall power absorption is affected. In this paper wake effects in the lee of a single WEC and multiple WECs of the overtopping type, where the water volume of overtopped waves is first captured in a basin above mean sea level and then drains back to the sea through hydro turbines, are studied using the time-dependent mild-slope equation model MILDwave. The wake behind a single WEC is investigated for long-crested and short-crested incident waves. The wake becomes wider for larger wave peak periods. An increasing directional spreading results in a faster wave regeneration and a shorter wake behind the WEC. The wake in the lee of multiple WECs is calculated for two different farm lay-outs, i.e. an aligned grid and a staggered grid, with varying lateral and longitudinal spacing. The wave power redistribution in and behind each farm lay-out is studied in detail using MILDwave. In general, the staggered grid results in the highest overall wave power absorption.

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Ancellin, Matthieu, Marlène Dong, Philippe Jean et Frédéric Dias. « Far-Field Maximal Power Absorption of a Bulging Cylindrical Wave Energy Converter ». Energies 13, n^o 20 (20 octobre 2020) : 5499. http://dx.doi.org/10.3390/en13205499.

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The maximal power that is absorbed by a wave energy converter can be estimated from the far-field behavior of the waves that are radiated by the device. For realistic estimates, constraints must be used to enforce restrictions on the set of admissible motions when deriving the maximal absorption width. This work is dedicated to the numerical computation of the maximal absorption width under constraints for devices with several non-trivial degrees of freedom. In particular, the method is applied to a model of SBM Offshore’s S3 wave energy converter, a bulging horizontal cylinder. The results are compared with a more classical approach, which consists of computing the linear dynamic response of the wave energy converter interacting with the waves. The far-field maximal absorption width can be seen as an upper bound to evaluate what would be the power captured by a perfect control strategy. The method also shows that the absorption width of the S3 wave energy converter is larger for wavelengths that are smaller than the device length. In practice, this means that S3 wave energy converters will be longer than the maximal wavelength to be captured on the targeted production site.

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Smith, Warren R. « Wave–structure interactions for the distensible tube wave energy converter ». Proceedings of the Royal Society A : Mathematical, Physical and Engineering Sciences 472, n^o 2192 (août 2016) : 20160160. http://dx.doi.org/10.1098/rspa.2016.0160.

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A comprehensive linear mathematical model is constructed to address the open problem of the radiated wave for the distensible tube wave energy converter. This device, full of sea water and located just below the surface of the sea, undergoes a complex interaction with the waves running along its length. The result is a bulge wave in the tube which, providing certain criteria are met, grows in amplitude and captures the wave energy through the power take-off mechanism. Successful optimization of the device means capturing the energy from a much larger width of the sea waves (capture width). To achieve this, the complex interaction between the incident gravity waves, radiated waves and bulge waves is investigated. The new results establish the dependence of the capture width on absorption of the incident wave, energy loss owing to work done on the tube, imperfect tuning and the radiated wave. The new results reveal also that the wave–structure interactions govern the amplitude, phase, attenuation and wavenumber of the transient bulge wave. These predictions compare well with experimental observations.

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Kurniawan, A., J. R. Chaplin, D. M. Greaves et M. Hann. « Wave energy absorption by a floating air bag ». Journal of Fluid Mechanics 812 (28 décembre 2016) : 294–320. http://dx.doi.org/10.1017/jfm.2016.811.

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A floating air bag, ballasted in water, expands and contracts as it heaves under wave action. Connecting the bag to a secondary volume via a turbine transforms the bag into a device capable of generating useful energy from the waves. Small-scale measurements of the device reveal some interesting properties, which are successfully predicted numerically. Owing to its compressibility, the device can have a heave resonance period longer than that of a rigid device of the same shape and size, without any phase control. Furthermore, varying the amount of air in the bag is found to change its shape and hence its dynamic response, while varying the turbine damping or the air volume ratio changes the dynamic response without changing the shape.

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Usha, T. « Power absorption by thin wave energy devices ». Applied Mathematical Modelling 14, n^o 6 (juin 1990) : 327–33. http://dx.doi.org/10.1016/0307-904x(90)90085-j.

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Anbarsooz, M., H. Rashki et A. Ghasemi. « Numerical investigation of front-wall inclination effects on the hydrodynamic performance of a fixed oscillation water column wave energy converter ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 233, n^o 2 (18 juin 2018) : 262–71. http://dx.doi.org/10.1177/0957650918783122.

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One of the main geometrical parameters of the fixed oscillating water column wave energy converters is the inclination angle of front wall. In this study, the effects of this parameter on the hydrodynamic performance of an oscillating water column is investigated using a fully nonlinear two-dimensional numerical wave tank, which is developed using the Ansys Fluent 15.0 commercial software. The accuracy of the developed wave tank is first examined by simulating an oscillating water column, having a front wall normal to the water-free surface, subjected to linear, small amplitude incident waves. The resultant absorption efficiencies are compared with available analytical data in the literature, where a good agreement was observed. Next, the simulations are performed for strongly nonlinear waves, up to the wave steepness of 0.069 ( H/L = 0.069), where H is the wave height and L is the wave length. Results show that the absorption efficiency of the oscillating water column decreases considerably as the wave height increases. Moreover, the maximum wave energy absorption efficiency for the highly nonlinear waves occurs at a pneumatic damping coefficient lower than that of the linear theory. Then, the absorption efficiency of the oscillating water column is determined for eight various front wall configurations at various incident wave periods. Results show that, the front walls that are slightly bent towards the inner region of the oscillating water column chamber are more efficient at some wave periods in comparison with the cases studied in this paper.

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Gkaraklova, Sofia, Pavlos Chotzoglou et Eva Loukogeorgaki. « Frequency-Based Performance Analysis of an Array of Wave Energy Converters around a Hybrid Wind–Wave Monopile Support Structure ». Journal of Marine Science and Engineering 9, n^o 1 (22 décembre 2020) : 2. http://dx.doi.org/10.3390/jmse9010002.

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In this paper, we investigate, in the frequency domain, the performance (hydrodynamic behavior and power absorption) of a circular array of four semi-immersed heaving Wave Energy Converters (WECs) around a hybrid wind–wave monopile (circular cylinder). The diffraction/radiation problem is solved by deploying the conventional boundary integral equation method. Oblate-spheroidal and hemispherical-shaped WECs are considered. For each geometry, we assess the effect of the array’s net radial distance from the monopile and of the incident wave direction on the array’s performance under regular waves. The results illustrate that by placing the oblate spheroidal WECs close to the monopile, the array’s power absorption ability is enhanced in the low frequency range, while the opposite occurs for higher wave frequencies. For hemispherical-shaped WECs, the array’s power absorption ability is improved when the devices are situated close to the monopile. The action of oblique waves, with respect to the WECs’ arrangement, increases the absorbed power in the case of oblate spheroidal WECs, while these WECs show the best power absorption ability among the two examined geometries. Finally, for the most efficient array configuration, consisting of oblate spheroidal WECs situated close to the monopile, we utilize an “active” Power Take-Off (PTO) mechanism, facilitating the consideration of a variable with frequency PTO damping coefficient. By deploying this mechanism, the power absorption ability of the array is significantly enhanced under both regular and irregular waves.

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Jiang, Qingfang, James D. Doyle et Ronald B. Smith. « Interaction between Trapped Waves and Boundary Layers ». Journal of the Atmospheric Sciences 63, n^o 2 (1 février 2006) : 617–33. http://dx.doi.org/10.1175/jas3640.1.

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Abstract The absorption of trapped lee waves by the atmospheric boundary layer (BL) is investigated based on numerical simulations and theoretical formulations. It is demonstrated that the amplitude of trapped waves decays exponentially with downstream distance due to BL absorption. The decay coefficient, α, defined as the inverse of the e-folding decay distance, is found to be sensitive to both surface momentum and heat fluxes. Specifically, α is larger over a rougher surface, associated with a more turbulent BL. On the other hand, the value of α decreases with increasing surface heating and increases with increasing surface cooling, implying that a stable nocturnal BL is more efficient in absorbing trapped waves than a typically deeper and more turbulent convective BL. A stagnant layer could effectively absorb trapped waves and increase α. Over the range of parameters examined, the absorption coefficient shows little sensitivity to wave amplitude. A relationship is derived to relate the surface reflection factor and the wave decay coefficient. Corresponding to wave absorption, there are positive momentum and negative energy fluxes across the boundary layer top, indicating that an absorbing BL serves as a momentum source and energy sink to trapped waves. Wave reflection by a shallow viscous layer with a linear shear is examined using linear theory, and its implication on BL wave absorption is discussed.

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Cramer, N. F. « Alfvén resonance absorption in electron-positron plasmas ». Proceedings of the International Astronomical Union 6, S274 (septembre 2010) : 224–27. http://dx.doi.org/10.1017/s1743921311006983.

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AbstractWaves propagating obliquely in a magnetized cold pair plasma experience an approximate resonance in the wavevector component perpendicular to the magnetic field, which is the analogue of the Alfvén resonance in normal electron-ion plasmas. Wave absorption at the resonance can take place via mode conversion to the analogue of the short wavelength inertial Alfvén wave. The Alfvén resonance could play a role in wave propagation in the pulsar magnetosphere leading to pulsar radio emission. Ducting of waves in strong plasma gradients may occur in the pulsar magnetosphere, which leads to the consideration of Alfvén surface waves, whose energy is concentrated in the region of strong gradients.

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Yang, Yongbiao, TingYan Zhang, Jinxuan Guo, Zhimin Zhang, Qiang Wang et Guojun Li. « Energy absorption within elastic range for AZ31 magnesium alloy ». Materials Research Express 8, n^o 10 (1 octobre 2021) : 106522. http://dx.doi.org/10.1088/2053-1591/ac3104.

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Abstract Energy absorption for AZ31 magnesium Alloy was investigated with Split Hopkinson Pressure Bar using single stress wave so as to avoid multiple stress wave loading. The stress wave amplitude, which was in elastic stress range and propagated along the AZ31 magnesium bar, was reduced with increasing propagating distance, and with increasing stress wave amplitude, the stress wave amplitude reduction along the magnesium bar was increased losing more energy as compared with that of the stress wave with lower amplitude. The drastically decreased stress wave amplitude could be explained based on dislocations movements, which was similar to the established theory of damping for the explanation of the energy loss during cyclic loading. However, it was not the case for LY12 aluminum alloy: the stress wave amplitude changed slightly without drastic energy loss regardless of the variation of stress wave amplitude.

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ARIKAWA, Taro, Koichiro KUBOTA, Kenichiro SHIMOSAKO, Masahide TAKEDA, Manabu IGARASHI, Masaru KATO, Yasukuni KANAYA, Kazuyoshi KIHARA, Yasushi HOSOKAWA et Tadayuki NAKAMURA. « A study on Wave Energy Absorption of Breakwater with OWC type Wave Energy Convertors ». Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 69, n^o 2 (2013) : I_1306—I_1310. http://dx.doi.org/10.2208/kaigan.69.i_1306.

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Lai, Wenbin, Yonghe Xie et Detang Li. « Numerical Study on the Optimization of Hydrodynamic Performance of Oscillating Buoy Wave Energy Converter ». Polish Maritime Research 28, n^o 1 (1 mars 2021) : 48–58. http://dx.doi.org/10.2478/pomr-2021-0005.

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Abstract The oscillating buoy wave energy converter (OBWEC) captures wave energy through the undulating movement of the buoy in the waves. In the process of capturing wave energy, the hydrodynamic performance of the buoy plays an important role. This paper designed the “Haida No. 1” OBWEC, in which the buoy adopts a form of swinging motion. In order to further improve the hydrodynamic performance of the buoy, a 2D numerical wave tank (NWT) model is established using ADINA software based on the working principle of the device. According to the motion equation of the buoy in the waves, the influence of the buoy shape, arm length, tilt angle, buoy draft, buoy width, wave height and Power Take-off (PTO) damping on the hydrodynamic performance of the buoy is studied. Finally, a series of physical experiments are performed on the device in a laboratory pool. The experimental results verify the consistency of the numerical results. The research results indicate that the energy conversion efficiency of the device can be improved by optimizing the hydrodynamic performance of the buoy. However, the absorption efficiency of a single buoy for wave energy is limited, so it is very difficult to achieve full absorption of wave energy.

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Zhang, Qing Hua, Hong Hui Sun et Hong Xia Wang. « Absorption Spectrum of Carbon Nanotubes ». Applied Mechanics and Materials 633-634 (septembre 2014) : 3–6. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.3.

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Carbon nanotubes are very typical nanomaterials, because the electron π of carbon nanotubes is restricted by the quantum size, the energy bands of the electron π are discontiguous and the characteristic of its energy level is divisive. The electron π can absorb the photon and makes transition from low energy level to high energy level, so it has the characteristic of wave-absorption . Based on the theory of quantum mechanics and the atomic structure of carbon nanotubes, the electronic energy bands and absorption spectrum of carbon nanotubes are analyzed in this paper, the results show that carbon nanotubes of different size correspond with absorption spectrum of different wave bands, and the computational results are afforded for the bases of designing wave-absorption materials.

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Guo, Yinjing, Yuanyuan Ju, Zhen Liu et Jianhua Zhang. « A Propagation Loss Coefficient Model of Low-Frequency Elastic Wave in Coal Strata Set ». Mathematical Problems in Engineering 2020 (9 mars 2020) : 1–7. http://dx.doi.org/10.1155/2020/6832362.

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Elastic waves cause energy loss during the transmission of coal measures. These losses include propagation loss, dielectric absorption loss, scattering loss, and frequency migration loss. The absorption loss is mainly caused by the inelastic absorption. The scattering loss is caused by the uneven heat absorption in the formation. The frequency shift loss is caused by the piezoelectric effect of coal-bearing formations and the intermodulation of different frequency signals. After considering the influence factors of the coal seam structure, this paper presents a model of low-frequency elastic waves loss coefficient. The paper proposed the loss coefficient of the elastic wave in the coal measure strata by considering two main attenuation mechanisms: intrinsic absorption and scattering. This paper theoretically studied the effects of the model parameters such as density, porosity, particle size, and wave frequency on the loss of wave energy using COMSOL simulation. Besides, the comparison of MATLAB simulation results shows that the simulation results produced by the model proposed in this paper are similar to the models embedded in COMSOL. This work can be applied to coal, oil, and gas exploration and is also helpful to study the mechanisms of wave attention on the low-frequency band.

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Yu, Xiao, Li Chen, Qin fang et Wuzheng Chen. « Stress Attenuation and Energy Absorption of the Coral Sand with Different Particle Sizes under Impacts ». Proceedings 2, n^o 8 (12 juillet 2018) : 545. http://dx.doi.org/10.3390/icem18-05440.

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The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of 1.18–0.60 mm, 0.60–0.30 mm, 0.30–0.15 mm, and 0.15–0.075 mm, were carefully sieved and tested. Significant effects of coral sand on stress wave attenuation and energy absorption were observed. Correlation between stress wave attenuation and energy absorption of coral sand was validated. Conclusions on particle size effect of stress wave attenuation and energy absorption, which support each other, were drawn. There existed a common critical stress zone for coral sand with different particle sizes. When the stress below this zone, sand with small particle sizes attenuates stress wave better and absorb energy more; when the stress beyond this zone, sand with larger particle sizes behave better on stress wave attenuation and energy absorption.

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Wu, Jinming. « On Power-Absorption Degrees of Freedom for Point Absorber Wave Energy Converters ». Journal of Marine Science and Engineering 8, n^o 9 (14 septembre 2020) : 711. http://dx.doi.org/10.3390/jmse8090711.

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Point absorbers are extensively employed in wave energy conversion. In this work, we studied the point absorber with the buoy of a vertical cylindrical shape. Wave power absorption is obtained through the relative motion between the buoy and an internal mass. Three power-absorption degrees of freedom are investigated, i.e., surge, heave, and pitch, together with the influence of wave compliance of the buoy. Results show that, to absorb more power, the internal mass should be as large as possible for power absorption in translational degrees of freedom, i.e., surge and heave. The total rotational inertia should be as large as possible and the center of mass should be as low as possible for power absorption in pitch. Wave compliance of the buoy slightly enhances the power absorption in surge, but significantly weakens the power absorption in pitch. Surge is the best degree of freedom for power absorption owing to the highest efficiency, indicated by the largest capture width ratio. The simple resistive control is found to be adequate for wave power absorption of the self-reacting point absorber.

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Gao, Hongtao, et Biao Li. « Establishment of Motion Model for Wave Capture Buoy and Research on Hydrodynamic Performance of Floating-Type Wave Energy Converter ». Polish Maritime Research 22, s1 (1 septembre 2015) : 106–11. http://dx.doi.org/10.1515/pomr-2015-0041.

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Abstract Floating-type wave energy converter has the advantages of high wave energy conversion efficiency, strong shock resistance ability in rough sea and stable output power. So it is regarded as a promising energy utilization facility. The research on hydrodynamic performance of wave capture buoys is the precondition and key to the wave energy device design and optimization. A simplified motion model of the buoys in the waves is established. Based on linear wave theory, the equations of motion of buoys are derived according to Newton’s second law. The factors of wave and buoys structural parameters on wave energy absorption efficiency are discussed in the China’s Bohai Sea with short wave period and small wave height. The results show that the main factor which affects the dynamic responses of wave capture buoys is the proximity of the natural frequency of buoys to the wave period. And the incoming wave power takes a backseat role to it at constant wave height. The buoys structural parameters such as length, radius and immersed depth, influence the wave energy absorption efficiency, which play significant factors in device design. The effectiveness of this model is validated by the sea tests with small-sized wave energy devices. The establishment methods of motion model and analysis results are expected to be helpful for designing and manufacturing of floating-type wave energy converter.

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Stansby, Peter, Efrain Carpintero Moreno, Sam Draycott et Tim Stallard. « Total wave power absorption by a multi-float wave energy converter and a semi-submersible wind platform with a fast far field model for arrays ». Journal of Ocean Engineering and Marine Energy 8, n^o 1 (19 octobre 2021) : 43–63. http://dx.doi.org/10.1007/s40722-021-00216-9.

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AbstractWave energy converters absorb wave power by mechanical damping for conversion into electricity and multi-float systems may have high capture widths. The kinetic energy of the floats causes waves to be radiated, generating radiation damping. The total wave power absorbed is thus due to mechanical and radiation damping. A floating offshore wind turbine platform also responds dynamically and damping plates are generally employed on semi-submersible configurations to reduce motion, generating substantial drag which absorbs additional wave power. Total wave power absorption is analysed here by linear wave diffraction–radiation–drag models for a multi-float wave energy converter and an idealised wind turbine platform, with response and mechanical power in the wave energy case compared with wave basin experiments, including some directional spread wave cases, and accelerations compared in the wind platform case. The total power absorption defined by capture width is input into a far field array model with directional wave spreading. Wave power transmission due a typical wind turbine array is only reduced slightly (less than 5% for a 10 × 10 platform array) but may be reduced significantly by rows of wave energy converters (by up to about 50%).

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Irzak M. A. et Nechaev S. A. « Full-wave 2D modeling of helicons propagation and absorption in the spherical tokamak Globus-M2 ». Technical Physics 92, n^o 3 (2022) : 282. http://dx.doi.org/10.21883/tp.2022.03.53717.239-21.

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Numerical modeling of propagation and absorption of fast waves (helicons) with frequency 200MHz in 2D inhomogeneous plasma of the spherical tokamak Globus-M2 was carried out with 2D full-wave code. Toroidal effects, poloidal magnetic field and the actual shape of the flux surfaces were taken into account. The full wave electric field and RF power absorption profiles were computed by solving plasma wave equation with electron Landau damping term. The modeling demonstrated a fairly high efficiency of helicons absorption in the bulk plasma within a wide range of experimental parameters. The waves propagate to the inner regions of the plasma column and are mainly absorbed there; less than 20% of RF energy returns back to the plasma periphery. Keywords: high temperature plasma, nuclear fusion, tokamak, high frequency plasma waves, helicons, plasma wave equation, full-wave code.

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Zhou, Xuan, Yu-Run Miao, William L. Shaw, Kenneth S. Suslick et Dana D. Dlott. « Shock Wave Energy Absorption in Metal–Organic Framework ». Journal of the American Chemical Society 141, n^o 6 (31 janvier 2019) : 2220–23. http://dx.doi.org/10.1021/jacs.8b12905.

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Noad, I. F., et R. Porter. « Approximations to Wave Energy Absorption by Articulated Rafts ». SIAM Journal on Applied Mathematics 77, n^o 6 (janvier 2017) : 2199–223. http://dx.doi.org/10.1137/16m1104743.

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Lu, Zhongyue, Jianzhong Shang, Zirong Luo, Chongfei Sun et Yiming Zhu. « Research on a new wave energy absorption device ». IOP Conference Series : Earth and Environmental Science 108 (janvier 2018) : 052021. http://dx.doi.org/10.1088/1755-1315/108/5/052021.

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Filianoti, Pasquale G. F., et Luana Gurnari. « A Field Experiment on Wave Forces on an Energy-Absorbing Breakwater ». Energies 13, n^o 7 (27 mars 2020) : 1563. http://dx.doi.org/10.3390/en13071563.

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The U-OWC is a caisson breakwater embodying a device for wave energy absorption. Under the wave action, the pressure acting on the upper opening of the vertical duct fluctuates, producing a water discharge alternatively entering/exiting the plant through the U-duct, formed by the duct and the chamber. The interaction between incoming waves and the water discharge alters the wave pressure distribution along the wave-beaten wall of this breakwater compared with the pressure distributions on a vertical pure reflecting wall. As a consequence, the horizontal wave forces produced on the breakwater are also different. A small scale U-OWC breakwater was put off the eastern coast of the Strait of Messina (Southern Italy) to measure the horizontal wave force. Experimental results were compared with Boccotti’s and Goda’s wave pressure formulas, carried out for conventional upright breakwaters, to check their applicability on the U-OWC breakwaters. Both models are suitable for design of U-OWC breakwaters even if they tend to overestimate by up to 25% the actual horizontal loads on the breakwater. Indeed, the greater the absorption of the energy is, the lower the wave pressure on the breakwater wall is.

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Göteman, Malin, Cameron McNatt, Marianna Giassi, Jens Engström et Jan Isberg. « Arrays of Point-Absorbing Wave Energy Converters in Short-Crested Irregular Waves ». Energies 11, n^o 4 (17 avril 2018) : 964. http://dx.doi.org/10.3390/en11040964.

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For most wave energy technology concepts, large-scale electricity production and cost-efficiency require that the devices are installed together in parks. The hydrodynamical interactions between the devices will affect the total performance of the park, and the optimization of the park layout and other park design parameters is a topic of active research. Most studies have considered wave energy parks in long-crested, unidirectional waves. However, real ocean waves can be short-crested, with waves propagating simultaneously in several directions, and some studies have indicated that the wave energy park performance might change in short-crested waves. Here, theory for short-crested waves is integrated in an analytical multiple scattering method, and used to evaluate wave energy park performance in irregular, short-crested waves with different number of wave directions and directional spreading parameters. The results show that the energy absorption is comparable to the situation in long-crested waves, but that the power fluctuations are significantly lower.

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Tiedeman, Simon Alexander, William Allsop, Viviana Russo et Andy Brown. « A DEMOUNTABLE WAVE ABSORBER FOR WAVE FLUMES AND BASINS ». Coastal Engineering Proceedings 1, n^o 33 (14 décembre 2012) : 37. http://dx.doi.org/10.9753/icce.v33.waves.37.

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Passive wave absorption is an integral component of the physical modeling environment, used to minimise unwanted reflections of wave energy that compromise test results. This paper reviews data for methods of passive absorbers and then extends this knowledge through the design and implementation of a device that can be removed from the working water surface. The modeling tests that were carried out in this paper demonstrate that a parabolic spending beach can perform by absorbing waves with coefficients of reflection Cr(energy) significantly

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Luo, Geng, et Pu Xue. « Investigations on Dynamic Energy Absorption Behavior of Metal Foam ». Key Engineering Materials 715 (septembre 2016) : 192–97. http://dx.doi.org/10.4028/www.scientific.net/kem.715.192.

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In this study, the dynamic energy absorption behavior of metal foam is investigated. A 3D Voronoi numerical model is established. Uniaxial compression under quasi-static and impact with velocities in the range of 10m/s to 200m/s are implemented, respectively, to investigate the energy behavior. During the impact process, the impact energy is transferred into kinetic energy and the internal energy. The kinetic energy varies with fluctuation due to the propagation and reflection of plastic shock wave. When the plastic shock wave arrives at the impact side or support side, the rate of internal energy absorption increases, and the kinetic energy possesses a local maximum/minimum value. The dynamic internal energy is obvious higher than quasi-static internal energy, due to the region behind the wave front is compacted tightly resulted from the plastic shock wave.

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Borgarino, B., A. Babarit et P. Ferrant. « Impact of wave interactions effects on energy absorption in large arrays of wave energy converters ». Ocean Engineering 41 (février 2012) : 79–88. http://dx.doi.org/10.1016/j.oceaneng.2011.12.025.

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Waters, R., M. Rahm, M. Eriksson, O. Svensson, E. Strömstedt, C. Boström, J. Sundberg et M. Leijon. « Ocean wave energy absorption in response to wave period and amplitude – offshore experiments on a wave energy converter ». IET Renewable Power Generation 5, n^o 6 (2011) : 465. http://dx.doi.org/10.1049/iet-rpg.2010.0124.

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Porter, Aaron K., Merrick C. Haller et Pukha Lenee-Bluhm. « LABORATORY OBSERVATIONS AND NUMERICAL MODELING OF THE EFFECTS OF AN ARRAY OF WAVE ENERGY CONVERTERS ». Coastal Engineering Proceedings 1, n^o 33 (15 décembre 2012) : 67. http://dx.doi.org/10.9753/icce.v33.management.67.

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This paper investigates the effects of wave energy converters (WECs) on water waves through the analysis of extensive laboratory experiments, as well as subsequent numerical simulations. Data for the analysis was collected during the WEC-Array Experiments performed at the O.H. Hinsdale Wave Research Laboratory at Oregon State University, in collaboration with Columbia Power Technologies, using five 1:33 scale point-absorbing WECs. The observed wave measurement and WEC performance data sets allowed for a direct computation of power removed from the wave field for a large suite of incident wave conditions and WEC array sizes. Using measured power absorption characteristics as a WEC parameterization for SWAN was developed. This parameterization was verified by comparison to the observational data set. Considering the complexity of the problem, the parameterization of WECs by only power absorption is a reasonable predictor of the effect of WECs on the far field.

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Stokes, Christopher, et Daniel Conley. « Modelling Offshore Wave farms for Coastal Process Impact Assessment : Waves, Beach Morphology, and Water Users ». Energies 11, n^o 10 (21 septembre 2018) : 2517. http://dx.doi.org/10.3390/en11102517.

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The emerging global wave energy industry has the potential to contribute to the world’s energy needs, but careful consideration of potential impacts to coastal processes in the form of an impact assessment is required for each new wave energy site. Methods for conducting a coastal processes impact assessment for wave energy arrays vary considerably in the scientific literature, particularly with respect to characterising the energy absorption of a wave energy converter (WEC) array in a wave model. In this paper, modelling methods used in the scientific literature to study wave farm impacts on coastal processes are reviewed, with the aim of determining modelling guidance for impact assessments. Effects on wave climate, beach morphology, and the surfing resource for coastal water users are considered. A novel parameterisation for the WEC array transmission coefficient is presented that, for the first time, uses the permitted power rating of the wave farm, which is usually well defined at the impact assessment stage, to estimate the maximum likely absorption of a permitted WEC array. A coastal processes impact assessment case study from a wave farm in south-west Ireland is used to illustrate the application of the reviewed methods, and demonstrates that using the new ‘rated power transmission coefficient’ rather than a WEC-derived transmission coefficient or complete energy absorption scenario can make the difference between significant and non-significant levels of coastal impacts being predicted.

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Sakr, Ahmed H., Sayed M. Metwalli et Yasser H. Anis. « Dynamics of Heaving Buoy Wave Energy Converters with a Stiffness Reactive Controller ». Energies 14, n^o 1 (23 décembre 2020) : 44. http://dx.doi.org/10.3390/en14010044.

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Heaving buoy wave energy converters (WEC) are floating oscillators, commonly modeled as single-degree-of-freedom vibrating systems. As the wave frequencies change according to the sea state, these devices must be controlled to maximize energy absorption. A new short-term reactive loading control technique is proposed that maximizes power absorption. The control is realized through tuning the effective stiffness of the vibrating system; thus, adjusting its natural frequency to meet the incident waves energy frequency achieving near-to-resonance operation and maximum power absorption. This stiffness is adjusted using an external stiffness, whose value is varied by a continuously variable transmission (CVT) mechanism connected to the buoy. The system equations were derived then solved analytically to calculate the controller bandwidth. Experiments demonstrated promising results for near-resonance tuning at different input frequencies. Results show that an optimized damping value exists at which power absorption can be significantly increased. The WEC equipped with the proposed reactive controller can provide faster tuning actions than long-term techniques. It also works on longer time intervals than phase-control methods; hence, reducing the continuous demands from the PTO system.

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Castellucci, Valeria, Mikael Eriksson et Rafael Waters. « Impact of Tidal Level Variations on Wave Energy Absorption at Wave Hub ». Energies 9, n^o 10 (19 octobre 2016) : 843. http://dx.doi.org/10.3390/en9100843.

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Oh, Jin-seok, et Jae-hee Jang. « OWC design to increase wave energy absorption efficiency in wave conversion systems ». Journal of Mechanical Science and Technology 29, n^o 7 (juillet 2015) : 2987–93. http://dx.doi.org/10.1007/s12206-015-0629-5.

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Camassa, Roberto, et Claudio Viotti. « On the response of large-amplitude internal waves to upstream disturbances ». Journal of Fluid Mechanics 702 (22 mai 2012) : 59–88. http://dx.doi.org/10.1017/jfm.2012.147.

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AbstractLarge-amplitude internal solitary waves generate shear flows that intensify from the wings of the waves to their maxima. Upstream perturbations of the hydrostatic equilibrium in the form of wave packets along the path of wave propagation are expected to trigger shear instability and ultimately generate Kelvin–Helmholtz roll-ups. In contrast, as shown here with accurate simulations of incompressible stratified Euler equations, large internal waves can act as suppressors of perturbations. The precise understanding of the mechanisms leading to different outcomes, including whether instability is excited, is the focus of this work. Under the action of shear flows, small-amplitude wave packets undergo stretching and filamentation, which lead to significant absorption of perturbation energy into the background shear. It is found that this typical behaviour is present in the self-induced shear by internal waves, regardless of whether the shear is stable or unstable, and can leave a quieter state in the wave’s wake for a wide range of perturbation parameters. In the unstable case, even once perturbations are selected to excite the instability, our results show that this absorption can act to reduce growth in the strong-shear region, effectively making roll-up development observable only downstream of the wave crest. Our approach is both analytical and numerical; a model valid for relatively thin pycnoclines and suitable for local spectral analysis is devised and used. Energy diagnostics on the simulations are implemented to validate the numerics and illustrate the energy exchanges between background wave flow and its shear. A link between the absorption mechanism and the clustering of local eigenvalues along the wave is proposed. This promotes an energetic coupling among neutral modes stronger than what may be expected to occur in slowly varying flows, and gives rise to multi-modal transient dynamics of the kind often referred to as non-normality effects. For those cases in which the wave-induced shear meets the conditions for local instability, it is found that the growth of disturbances is selective with respect to the sign of the mode excited upstream. Elements of this phenomenon are interpreted by asymptotic analysis for spatial growth in time-independent slowly varying media.

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Bao, Lingjie, Ying Wang, Chuhua Jiang, Junhua Chen, Hao Li et Shenghu Wang. « Research on Wave and Energy Reduction Performance of Floating Breakwater Based on S-Shaped Runner ». Energies 15, n^o 14 (15 juillet 2022) : 5148. http://dx.doi.org/10.3390/en15145148.

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Aiming at the breeding environment where the construction of marine pastures requires low wind and waves, a floating breakwater (FB) with a Savonius type (referred to as S type) runner with wave absorption and energy reduction function is studied for wave absorption and energy reduction in aquaculture sea areas. The wave-absorbing and energy-reducing performance of the floating breakwater is studied by the method of combining numerical simulation and experiment. Using Star-CCM+ numerical simulation software, based on linear wave theory and energy conservation law, using overlapping grid technology, calling DFBI model, second-order time discretization, a three-dimensional flow field model of the floating breakwater was established and numerically simulated. At the same time, a floating breakwater physical test system was developed for experimental verification, the transmission wave and the conversion power consumption of the S-shaped runner under different wave heights and different periods were measured, and the results Please carefully check the accuracy of names and affiliations. of numerical simulation and physical experiments were comprehensively evaluated. The research results show that the floating breakwater based on the S-shaped runner has the functions of reducing the wave height and reducing the wave energy, which have guiding significance for practical engineering.

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Ирзак, М. А., et С. А. Нечаев. « Полноволновое двумерное моделирование распространения и поглощения геликонов в плазме сферического токамака Глобус-М2 ». Журнал технической физики 92, n^o 3 (2022) : 353. http://dx.doi.org/10.21883/jtf.2022.03.52131.239-21.

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Numerical modeling of propagation and absorption of fast waves (helicons) with frequency 200 MHz in 2D inhomogeneous plasma of the spherical tokamak Globus-M2 was carried out with 2D full-wave code. Toroidal effects, poloidal magnetic field and the actual shape of the flux surfaces were taken into account. The full wave electric field and RF power absorption profiles were computed by solving plasma wave equation with electron Landau damping term. The modeling demonstrated a fairly high efficiency of helicons absorption in the bulk plasma within a wide range of experimental parameters. The waves propagate to the inner regions of the plasma column and are mainly absorbed there; less than 20% of RF energy returns back to the plasma periphery.

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Trainiti, G., Y. Ra'di, M. Ruzzene et A. Alù. « Coherent virtual absorption of elastodynamic waves ». Science Advances 5, n^o 8 (août 2019) : eaaw3255. http://dx.doi.org/10.1126/sciadv.aaw3255.

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Absorbers suppress reflection and scattering of an incident wave by dissipating its energy into heat. As material absorption goes to zero, the energy impinging on an object is necessarily transmitted or scattered away. Specific forms of temporal modulation of the impinging signal can suppress wave scattering and transmission in the transient regime, mimicking the response of a perfect absorber without relying on material loss. This virtual absorption can store energy with large efficiency in a lossless material and then release it on demand. Here, we extend this concept to elastodynamics and experimentally show that longitudinal motion can be perfectly absorbed using a lossless elastic cavity. This energy is then released symmetrically or asymmetrically by controlling the relative phase of the impinging signals. Our work opens previously unexplored pathways for elastodynamic wave control and energy storage, which may be translated to other phononic and photonic systems of technological relevance.

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Luan, He, Zhang, Jing, Jin, Geng et Liu. « Study on the Optimal Wave Energy Absorption Power of a Float in Waves ». Journal of Marine Science and Engineering 7, n^o 8 (13 août 2019) : 269. http://dx.doi.org/10.3390/jmse7080269.

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The utilization of ocean renewable energy, especially wave energy, is of great significance in ocean engineering. In this study, a three-dimensional numerical wave tank was established to simulate the wave-float interaction based on the Reynolds-averaged Navier–Stokes equations and the Realizable K-Epsilon Two-Layer turbulence model was applied. Firstly, convergence studies with respect to the mesh and time step were carried out and confirmed by the published analytical and numerical data. Then, the resonance condition of a particular float was solved by both numerical and analytical methods. The numerical and the analytical results are mutually verified in good agreements, which verify the reliability of the analytical process. Furthermore, a wave energy converter (WEC) consisting of a single float without damping constant was adopted, and its hydrodynamic performance in different wave conditions was investigated. It was found that the damping factor can affect the motion response of the float and the wave force it receives. Under a certain wavelength condition, the WEC resonates with the wave, at which the wave force on the float, displacement of the float and other parameters reach a maximum value. Finally, the influence of linear damping constant on the power take-off (PTO) was studied. The results show that the damping factor does not affect the wave number turning point of the optimal damping constant.

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Li, Ai-jun, et Yong Liu. « Hydrodynamic performance and energy absorption of multiple spherical absorbers along a straight coast ». Physics of Fluids 34, n^o 11 (novembre 2022) : 117102. http://dx.doi.org/10.1063/5.0118052.

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The development and utilization of wave energy have great potentiality to alleviate the urgent problem of global energy shortage. Spherical bodies can be used as point absorbers to extract wave energy, and much attention has been paid to the performance of spherical absorbers in an open water domain. This study focuses on the hydrodynamic performance and energy absorption of multiple spherical absorbers in front of a straight coast. The coast is assumed to be a fully reflecting vertical wall, and all the absorbers are restricted to only heave motion. An analytical solution based on linear potential flow theory is developed for the problem of wave diffraction and radiation by multiple absorbers. In the solution procedure, the hydrodynamic problem is transformed into an equivalent problem in an open water domain by applying the image principle. The velocity potential of the fluid motion is solved using the method of multipole expansions combined with the shift of local spherical coordinate systems. Then, the wave excitation force, added mass coefficient, radiation damping coefficient, and energy extraction performance of the absorbers are calculated. Case studies are presented to analyze the effects of the coastal reflection and hydrodynamic interaction among absorbers on the energy extraction performance of the wave energy converter (WEC) system. The effects of wave frequency, incident angle, spacing between the absorber and coast, submergence depth, absorber number, and plane layout are also clarified. The results suggest that the energy extraction performance of an isolated absorber is significantly improved when the motions of the waves and absorber are in resonance, and the coastal reflection can enhance the overall energy extraction performance for a WEC system with multiple absorbers. In addition, when the number of absorbers increases, the effects of the coastal reflection and hydrodynamic interaction become more complicated.

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Li, Yaokun, Jiping Chao et Yanyan Kang. « Variations in Wave Energy and Amplitudes along the Ray Paths of Barotropic Rossby Waves in Horizontally Non-Uniform Basic Flows ». Atmosphere 12, n^o 4 (5 avril 2021) : 458. http://dx.doi.org/10.3390/atmos12040458.

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A non-divergent barotropic model on a sphere transformed to Mercator coordinates is used to examine the variations in wave energy and amplitude along the energy dispersion paths of barotropic Rossby waves in non-uniform basic flows. Wave energy can be easily solved by specifying the divergence of the group velocity along the corresponding rays. In an analytical non-uniform basic flow that represents the basic features of the observed one at middle latitudes, waves with different periods decay accompanying the decreases in wave energy and amplitude and the increase in the total wavenumber. This implies that the waves are trapped and the energy is eventually absorbed by the basic flow. For the observed non-uniform basic flow that can represent the basic features of the non-divergent wind field at 200 hPa, the situation is more complicated. The significant increase in wave energy can be caused by either the convergence of wave energy or the barotropic energy absorption from the basic flow or both of them. A significant increase in amplitude can also be observed if the total wavenumber varies moderately. This means waves can significantly develop. Waves may decay if both wave energy and amplitude decrease. Waves may propagate without significant developing or decaying to realize a long distance propagation. The propagating waves are mainly caused by oscillating wave energy as well as amplitude.

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Moroz, P. E., et P. L. Colestock. « Electron absorption of fast waves in global wave calculations ». Plasma Physics and Controlled Fusion 33, n^o 5 (1 mai 1991) : 417–31. http://dx.doi.org/10.1088/0741-3335/33/5/002.

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Zuo, Jingying, Silong Zhang, Jiang Qin, Wen Bao, Cui Naigang et Xiaoyong Liu. « Interaction mechanism between shock waves and supersonic film cooling with cracking reaction ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 234, n^o 3 (6 décembre 2019) : 908–23. http://dx.doi.org/10.1177/0954410019892178.

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In order to understand the interaction mechanism between shock waves and supersonic film cooling with cracking reaction, supersonic film cooling using gaseous hydrocarbon fuel as coolant in terms of cracking reaction of the coolant, with and without shock waves interaction, is investigated numerically. Theoretically, cracking reaction may be accelerated by the shock wave interaction, which may enhance the mixing of the coolant and absorb heat, which will lead to contradictory effects on supersonic film cooling. However, it turns out that, with shock waves interaction, cracking reaction only absorbs more heat but barely has any effect on the mixing either locally or further downstream due to the momentum change caused by the reaction is extremely small and the energy change plays the dominate role. It is worth mentioning that oblique shock wave causes energy accumulation in the shock wave interaction region, which deteriorates supersonic film cooling. However, with the cracking reaction considered, the negative effect brings by the oblique shock wave is weakened by the cracking reaction due to the increment of chemical heat absorption caused by the energy change. It is found that the absolute temperature in the shock wave interaction and the relative temperature increment caused by the shock wave interaction to be the decisive factors of the chemical heat absorption increment, especially for high absolute temperature or relative temperature increments, and the effect of the local reactant concentration plays the dominant role. Furthermore, the extent of weakened chemical reaction on the negative effect due to the oblique shock wave depends not only on the chemical heat absorption but also on the local absolute temperature.

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Smith, Ronald B., Qingfang Jiang et James D. Doyle. « A Theory of Gravity Wave Absorption by a Boundary Layer ». Journal of the Atmospheric Sciences 63, n^o 2 (1 février 2006) : 774–81. http://dx.doi.org/10.1175/jas3631.1.

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Abstract A one-layer model of the atmospheric boundary layer (BL) is proposed to explain the nature of lee-wave attenuation and gravity wave absorption seen in numerical simulations. Two complex coefficients are defined: the compliance coefficient and the wave reflection coefficient. A real-valued ratio of reflected to incident wave energy is also useful. The key result is that, due to horizontal friction, the wind response in the BL is shifted upstream compared to the phase of disturbances in the free atmosphere. The associated flow divergence modulates the thickness of the BL so that it partially absorbs incident gravity waves. A simple expression is derived relating the reflection coefficient to the attenuation and wavelength shift of trapped lee waves. Results agree qualitatively with the numerical simulations, including the effects of increased surface roughness and heat flux.

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Zhang, Xiaoxia, Qiang Zeng et Zhen Liu. « Hydrodynamic Performance of Rectangular Heaving Buoys for an Integrated Floating Breakwater ». Journal of Marine Science and Engineering 7, n^o 8 (24 juillet 2019) : 239. http://dx.doi.org/10.3390/jmse7080239.

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Recently, the integrated development of wave energy converters and breakwaters has become popular, moving from traditional passive wave absorption to active energy capture. In this study, rectangular heaving buoys are considered as floating breakwater modules to absorb wave energy. A numerical wave tank is established based on Reynolds Averaged Navier-Stokes equation and User-Define-Function in ANSYS-Fluent commercial software. The numerical results show that incident wave conditions and submerged depth have significant effects on the heaving performance and wave energy absorption of a rectangular buoy. Flow structures around the buoy are shown to exhibit flow separations and vortex shedding, which can provide more information on buoy optimization. Power take-off (PTO) reaction forces are assumed to be a linear function of the translation velocities of the buoy. Numerical results demonstrate that a suitable PTO module can improve the wave power absorption by up to 34.2% for certain buoy and wave conditions, which is valuable for further investigations.

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Ukhtary, M. Shoufie, Eddwi H. Hasdeo, Ahmad R. T. Nugraha et Riichiro Saito. « Fermi energy-dependence of electromagnetic wave absorption in graphene ». Applied Physics Express 8, n^o 5 (22 avril 2015) : 055102. http://dx.doi.org/10.7567/apex.8.055102.

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Liu, Hailong, et Guoxin Cao. « Interaction between Mechanical Wave and Nanoporous Energy Absorption System ». Journal of Physical Chemistry C 117, n^o 8 (14 février 2013) : 4245–52. http://dx.doi.org/10.1021/jp310028x.

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Cai, Chunpei. « Energy Deposition/Absorption Effects on a Planar Shock Wave ». Journal of Thermophysics and Heat Transfer 21, n^o 1 (janvier 2007) : 252–54. http://dx.doi.org/10.2514/1.27970.

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