Multi-DOF WEC Performance in Variable Bathymetry Regions Using a Hybrid 3D BEM and Optimization

Bonovas, Markos; Belibassakis, Kostas; Rusu, Eugen

doi:10.3390/en12112108

Cited by 14 publications

(13 citation statements)

References 23 publications

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“…With respect to WECs arrays in front of breakwaters, surge oscillating WECs placed successively in the interior of a series of U-shaped openings (harbours) embedded in a "pure" reflecting wall have been investigated in [16], while all other relevant existing studies so far deal with arrays of cylindrical-shaped heaving WECs, in contrast to the case of isolated WECs arrays, where non-cylindrical heaving devices have been also utilized (e.g., [17][18][19]). Specifically, the power absorption of a linear array of five cylindrical heaving WECs in front of a bottom-mounted vertical wall of infinite length was examined and evaluated in [20] in both frequency and time domain, by also utilizing the method of images.…”

Section: Introductionmentioning

confidence: 99%

Performance of an Array of Oblate Spheroidal Heaving Wave Energy Converters in Front of a Wall

Loukogeorgaki

Boufidi

Chatjigeorgiou

2020

Water

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In this paper, we investigate the performance of a linear array of five semi-immersed, oblate spheroidal heaving Wave Energy Converters (WECs) in front of a bottom-mounted, finite-length, vertical wall under perpendicular to the wall regular waves. The diffraction and radiation problems are solved in the frequency domain by utilizing the conventional boundary integral equation method. Initially, to demonstrate the enhanced absorption ability of this array, we compare results with the ones corresponding to arrays of cylindrical and hemisphere-shaped WECs. Next, we investigate the effect of the array’s distance from the wall and of the length of the wall on the physical quantities describing the array’s performance. The results illustrate that the array’s placement at successively larger distances from the wall, up to three times the WECs’ radius, induces hydrodynamic interactions that improve the array’s hydrodynamic behavior, and thus its power absorption ability. An increase in the length of the wall does not lead to any significant power absorption improvement. Compared to the isolated array, the presence of the wall affects positively the array’s power absorption ability at specific frequency ranges, depending mainly on the array’s distance from the wall. Finally, characteristic diffracted wave field patterns are presented to interpret physically the occurrence of the local minima of the heave exciting forces.

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Section: Introductionmentioning

confidence: 99%

Performance of an Array of Oblate Spheroidal Heaving Wave Energy Converters in Front of a Wall

Loukogeorgaki

Boufidi

Chatjigeorgiou

2020

Water

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“…Following previous works [32,33], concerning the investigation and modeling of marine renewable energy systems, the present method focused on the estimation of the effect of wave-induced responses on the performance index of a twin-hull FPV structure in various sea conditions, as defined by the wave climatology of the offshore-coastal site where the system was deployed. As an example, the results concerning the performance index that is associated with the wave effects (Equation ( 20)) of the floating twin-hull structure of breadth B (T) = 20 m at a water depth h = 30 m that are presented and discussed above are given in Table 1 for wind waves corresponding to the Beaufort scale from BF = 1 (relatively calm sea) to BF = 5 − 6 conditions.…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamic Analysis of Twin-Hull Structures Supporting Floating PV Systems in Offshore and Coastal Regions

2021

Self Cite

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In this paper, a novel model based on the boundary element method (BEM) is presented for the hydrodynamic analysis of floating twin-hull structures carrying photovoltaic panels, supporting the study of wave responses and their effects on power performance in variable bathymetry regions. The analysis is restricted to two spatial dimensions for simplicity. The method is free of any mild-slope assumptions. A boundary integral representation is applied for the near field in the vicinity of the floating body, which involved simple (Rankine) sources, while the far field is modeled using complete (normal-mode) series expansions that are derived using separation of variables in the constant depth half-strips on either side of the middle, non-uniform domain, where the depth exhibited a general variation, overcoming a mild bottom-slope assumption. The numerical solution is obtained by means of a low-order panel method. Numerical results are presented concerning twin-hull floating bodies of simple geometry lying over uniform and sloping seabeds. With the aid of systematic comparisons, the effects of the bottom slope and curvature on the hydrodynamic characteristics (hydrodynamic coefficients and responses) of the floating bodies are illustrated and discussed. Finally, the effects of waves on the floating PV performance are presented, indicating significant variations of the performance index ranging from 0 to 15% depending on the sea state.

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“…Especially, ocean wave energy, as a choice of alternative form of energy supply, is attractive since it has the second largest potential among all ocean renewable energy sources [4]. However, since ocean energy technologies face several bottlenecks concerning survivability aspects, lack of grid availability and environmental and administrative issues [5], the wave energy sector is focusing on Wave Energy Converter (WEC) types either isolated or placed in an array for near-shore installation and operation [6,7]. The installation of a WEC system into other maritime structures such as a breakwater or a harbor, so as to supply wave power to the shore, can increase the system's efficiency by taking advantage of the scattered and the reflected waves from the vertical wall reducing in parallel the intensity of wave action on the shore [8,9].…”

Section: Introductionmentioning

confidence: 99%

Wave Power Absorption by Arrays of Wave Energy Converters in Front of a Vertical Breakwater: A Theoretical Study

Konispoliatis

Mavrakos

2020

Energies

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The present paper deals with the theoretical evaluation of the efficiency of an array of cylindrical Wave Energy Converters (WECs) having a vertical symmetry axis and placed in front of a reflecting vertical breakwater. Linear potential theory is assumed, and the associated diffraction and motion radiation problems are solved in the frequency domain. Axisymmetric eigenfunction expansions of the velocity potential are introduced into properly defined ring-shaped fluid regions surrounding each body of the array. The potential solutions are matched at the boundaries of adjacent fluid regions by enforcing continuity of the hydrodynamic pressures and redial velocities. A theoretical model for the evaluation of the WECs’ performance is developed. The model properly accounts for the effect of the breakwater on each body’s hydrodynamic characteristics and the coupling between the bodies’ motions and the power take-off mechanism. Numerical results are presented and discussed in terms of the expected power absorption. The results show how the efficiency of the array is affected by (a) the distance between the devices and the wall, (b) the shape of the WEC array configuration, as well as (c) the angle of the incoming incident wave.

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Multi-DOF WEC Performance in Variable Bathymetry Regions Using a Hybrid 3D BEM and Optimization

Cited by 14 publications

References 23 publications

Performance of an Array of Oblate Spheroidal Heaving Wave Energy Converters in Front of a Wall

Performance of an Array of Oblate Spheroidal Heaving Wave Energy Converters in Front of a Wall

Hydrodynamic Analysis of Twin-Hull Structures Supporting Floating PV Systems in Offshore and Coastal Regions

Wave Power Absorption by Arrays of Wave Energy Converters in Front of a Vertical Breakwater: A Theoretical Study

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