Theoretical performance investigation of a vertical cylindrical oscillating water column device in front of a vertical breakwater

Konispoliatis, Dimitrios N.; Mavrakos, Spyros A.

doi:10.1007/s40722-019-00147-6

Cited by 9 publications

(8 citation statements)

References 31 publications

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“…It is clear that the best place for placing wave energy converters is where the wave runup is high. Many researchers ( [20,21]) have studied the performance of wave energy converters placed in front of a breakwater. Moreover, the wave run-up information is useful in designing the freeboard to prevent wave overtopping.…”

Section: Hydrodynamic Results Of Polygonal Platformsmentioning

confidence: 99%

Hydrodynamic Behaviour of Floating Polygonal Platforms under Wave Action

Park¹,

Wang²

2021

JMSE

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The hydrodynamic behaviour of floating regular polygonal platforms under wave action was studied by conducting parametric studies. Considering triangular, square, hexagonal, and circular platforms of similar size and draft, the results show that their added mass, radiation damping, and RAOs are similar. However, the wave exciting forces are slightly different, particularly the horizontal forces. The polygonal platforms oriented with one of its corners in line with the prevailing wave direction can lead to a reduction in the horizontal force on the platform, a feature that helps in reducing the cost of a mooring system. Moreover, such oriented platforms are able to disperse the waves better in multiple directions and hence will not pose problems for ships or marine vessels passing by the platform on the weather side. Thus, the orientation of a polygonal platform is an important design consideration. From the comparison study among different polygonal platforms, their wave attenuation performances are slightly similar. The hydrodynamic analyses performed herein for the parametric studies were sped up considerably by using a significantly lesser number of Fourier coefficient sets for the series functions that define the velocity potentials when compared to those used by previous researchers in their analytical approaches. The adoption of the radius function defined by cosine-type radial perturbation does not only generate the geometric boundaries of polygonal platforms, but it also simplifies the formulation and quickens the computations.

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Section: Hydrodynamic Results Of Polygonal Platformsmentioning

confidence: 99%

Hydrodynamic Behaviour of Floating Polygonal Platforms under Wave Action

Park¹,

Wang²

2021

JMSE

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“…Concerning the OWC device, it had an outer radius α; inner radius α/b = 1.25; draught h 1 ; floating also in water depth d = 7.14α. For the shake of comparisons of numerical results with the heaving device case, the OWC's air turbine characteristics were considered equal to the Λ opt value of a similar OWC in isolation condition at the pumping resonance wave frequency [18]. Furthermore, the distances between the center of both examined WEC and the vertical walls were assumed equal, i.e., L 1 = L 2 (see Figures 1 and 2).…”

Section: Test Casesmentioning

confidence: 99%

“…In addition, floating WEC-breakwaters consisting of rectangular caissons and multiple pontoons have been investigated in [15][16][17]. Regarding WECs located in front of a linear vertical wall and particularly OWC devices considered either alone in the wave field or as part of an array, recent studies [18,19] have shown the amplification of the devices' efficiency due to the presence of a vane-type breakwater. Additionally, a linear breakwater with parabolic openings, as a parabolic reflector, has been studied to converge propagating waves toward a focus point, in which the wave height is further amplified compared to the wave height in front of a vane-type vertical wall [20].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Efficiency of a Wave Energy Converter in Front of an Orthogonal Breakwater

Konispoliatis

Mavrakos

2021

JMSE

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In the present study, the hydrodynamic efficiency of a cylindrical wave energy converter (WEC) of vertical symmetry axis and arranged in front of a reflecting orthogonal breakwater is explored. The idea is based on exploiting the anticipated amplification of the scattered and the reflected wave fields originating from the presence of the vertical walls, towards increasing the WEC’s wave power absorption due to the walls’ wave reflections. Two types of converters are examined, namely the heaving device and the oscillating water column (OWC) device, assuming linear potential theory. The associated diffraction-, motion-, and pressure-radiation problems are solved using axisymmetric eigenfunction expansions for the velocity potential around the WECs by properly accounting for the wave field’s modification due to the walls’ presence. To this end, a theoretical formulation dealing with the evaluation of the converter’s performance is presented accounting for the coupling between the WEC and the reflecting vertical walls. The results depict that the amount of the harvested wave power by the WEC in front of an orthogonal wall is amplified compared to the absorbed wave power by the same WEC in the open sea.

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“…Indicative theoretical and experimental studies concerning the effect of a vertical wall on the hydrodynamic characteristics of an array of five floating cylindrical bodies are studied in References [33,34], whereas, in Reference [35], the resonances of a freely floating half immersed cylinder in front of a vertical rigid breakwater have been investigated. Additionally, in References [36][37][38][39][40][41], the corresponding wave diffraction problem, as well as the motionand pressure-radiation problems of a single truncated cylinder and of an oscillating water column wave energy converter (WEC), placed in front of a vertical wall, was examined.…”

Section: Body-breakwater Simulation Methodsmentioning

confidence: 99%

Mean Drift Forces on Vertical Cylindrical Bodies Placed in Front of a Breakwater

Konispoliatis

Mavrakos

2020

Fluids

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This paper presents a numerical and experimental investigation of the second-order steady horizontal and vertical drift forces acting on cylindrical bodies in regular waves. The examined bodies are either kept restrained in front of a vertical breakwater or are considered free- floating when alone in the wave field. Two principally different approaches for mean drift forces determination are described: the momentum conservation principle and the direct integration of all pressure contributions upon the instantaneous wetted surface of the bodies, whereas, for the solution of the associated diffraction and motion radiation problems, analytical and panel methodologies are applied. The hydrodynamic interaction phenomenon between the bodies and the adjacent breakwater are taken into account by using the method of images. Theoretical and numerical results, concerning the horizontal and the vertical drift forces, are presented and compared with each other. Furthermore, additional comparisons are made with experimental data obtained during an experimental campaign at French research institute for exploitation of the sea (IFREMER), in France.

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Theoretical performance investigation of a vertical cylindrical oscillating water column device in front of a vertical breakwater

Cited by 9 publications

References 31 publications

Hydrodynamic Behaviour of Floating Polygonal Platforms under Wave Action

Hydrodynamic Behaviour of Floating Polygonal Platforms under Wave Action

Hydrodynamic Efficiency of a Wave Energy Converter in Front of an Orthogonal Breakwater

Mean Drift Forces on Vertical Cylindrical Bodies Placed in Front of a Breakwater

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