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

Abstract

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.

Hydrodynamic Efficiency of a Wave Energy Converter in Front of an Orthogonal 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]. Furthermore, the efficiency of an array of heaving WECs located in front of a linear breakwater has been studied recently in [21][22][23]. In these investigations, the method of images [24,25] was utilized to simulate the presence of the vertical wall, thus a fully reflecting, bottom seated, surface piercing breakwater of infinite length was considered.…”

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

“…Having determined the velocity potential around each body of the array, either with the matched axisymmetric eigenfunctions expansions (see Section 2.1) or the sink source technique, the exciting forces and the hydrodynamic coefficients of the bodies, as well as their motions and rotations can be evaluated. This analysis has been thoroughly described in References [41,53], thus, no further elaboration is provided here. An indicative representation of the motion equation system of an array of N bodies placed in front of a breakwater is presented in the Appendix A.…”

Layout optimization of heaving Wave Energy Converters linear arrays in front of a vertical wall

“…Under the same assumption, the performance of a linear, parallel, or perpendicular to the wall, array of five vertical axisymmetric (cylindrical or conical or semispherical) heaving WECs was investigated in Refs. [16,17]. The existence of a finite length leeward wall was considered in Refs.…”