Experimental study on the hydrodynamic performance of a multi-DOF WEC-type floating breakwater

A hybrid system consisting of wave energy converters and breakwaters can be applied for both wave energy conversion and shoreline protection. Besides, the cost of wave energy conversion is believed to be reduced by such a combination. In this paper, a two-dimensional asymmetric wave energy converter-type breakwater with a triangle-baffle bottom that can convert wave energy through its heave motion is proposed and investigated experimentally in regular waves. A supporting system is designed and established to allow the model to move in a single degree of freedom or prescribed combination of multiple-degree-of-freedoms. The effects of the geometric asymmetry, the bottom slope, the width-to-draft ratio, and the multiple-degree-of-freedom motion on the wave energy conversion and attenuation performances are analyzed. The results show that the triangle-baffle wave energy converter-type breakwater has much higher wave energy conversion efficiency than its rectangular counterpart with the same displacement. Increasing the bottom slope and allowing pitch motion can improve efficiency, allowing surge motion will reduce efficiency, and the effect of increasing the width is uncertain due to two conflicting effects. The asymmetry, bottom slope, and width only have a limited influence on the wave attenuation, whereas surge and pitch motions reduce the wave attenuation in short waves, analogizing a wavemaker.