Wave power extraction performance from Edinburgh Duck WEC integrated with floating breakwater

The performance of the Edinburgh Duck wave energy converter (ED-WEC) shows great potential when integrated with oceanic structures. In the present study, the wave energy extraction performance of an ED-WEC integrated with a box-type floating breakwater (FBW) is investigated based on small-amplitude wave theory, with the aim of harnessing maximum wave energy from the scattered and reflected waves in the presence of offshore structures. The scattered and reflected waves from marine structures approach the WEC, which, in turn, increases the wave power absorption of the WEC. The associated scattered and reflected waves for wave interactions with hybrid structures are studied, and the capture width ratio (CWR), wave power absorption, motion amplitude, and mean interaction factors of the ED–FBW hybrid system are discussed. The hydrodynamic coefficients play an important role in evaluating the CWR, wave power absorption, and mean interaction factor. The numerical results are analyzed for different structural and geometrical parameters, such as the width of the ED, the draft of the ED, the distance between the ED-WEC and the FBW, and the wave incident angle. Further, the numerical results obtained for the box-type FBW are compared with those for trapezoidal-type FBW, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im1"> <mml:mrow> <mml:mi>π</mml:mi> <mml:mtext>-type</mml:mtext> </mml:mrow> </mml:math> FBW, parabolic type FBW and semi-circular type FBW. The power absorbed <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im2"> <mml:mrow> <mml:msub> <mml:mi>P</mml:mi> <mml:mrow> <mml:mi>a</mml:mi> <mml:mi>b</mml:mi> <mml:mi>s</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> by the integrated ED-WEC is noted to increase in the narrow region of wave period. In addition, the increase in draft of the ED results in increase of submergence volume and variation in the hydrodynamic coefficients. In the case of an isolated system for deep water depth, the variation in CWR in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im3"> <mml:mrow> <mml:msub> <mml:mi>ξ</mml:mi> <mml:mrow> <mml:mn>33</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> is observed to be within <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im4"> <mml:mrow> <mml:mn>4.16</mml:mn> <mml:mo>%</mml:mo> <mml:mo>&lt;</mml:mo> <mml:mi>C</mml:mi> <mml:mi>W</mml:mi> <mml:mi>R</mml:mi> <mml:mo>&lt;</mml:mo> <mml:mn>31.25</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> while in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im5"> <mml:mrow> <mml:msub> <mml:mi>ξ</mml:mi> <mml:mrow> <mml:mn>44</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> , it is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" id="im6"> <mml:mrow> <mml:mn>52.54</mml:mn> <mml:mo>%</mml:mo> <mml:mo>&lt;</mml:mo> <mml:mi>C</mml:mi> <mml:mi>W</mml:mi> <mml:mi>R</mml:mi> <mml:mo>&lt;</mml:mo> <mml:mn>66.1</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> . The study performed will be helpful in optimizing the ED-WEC-FBW configuration in the real sea state condition and provide a potential solution of generating power along with the coastal defence structure.