Experimental and numerical investigation of WEC-type floating breakwaters: A single-pontoon oscillating buoy and a dual-pontoon oscillating water column

Wave energy converters(WECs) integrated into floating breakwaters or, more generally, their designs also used as wave absorbers can provide a space- and cost-sharing solution to enhance the efficiency of coastal protection. In this study, hydrodynamic performances an oscillating buoy(OB)-type single-pontoon breakwater(SPFB) water column(OWC)-type dual-pontoon breakwaters(DPFB) are evaluated, respectively, comprehensively compared with each other. A series physical experiments were conducted investigate effects parameters, geometrical dimensions, gap distances PTO damping coefficients. Numerical simulations based on fully nonlinear potential flow theory cross-check measured data, help further understand contribution higher-order waves. It is found that both attenuation conversion OWC-type DPFB non-uniform draft (i.e. shallow front-pontoon deep back-pontoon draft) better than those OB-type SPFB same displacement. Meanwhile, for DPFB, larger ratio chamber width total pontoon has beneficial effect attenuation, but adverse maximum efficiency. Under premise draft, OWC optimal opening higher OB damping, effective frequency bandwidth almost identical between two devices. Strong nonlinearity generate dissipation induced by viscous vortices, resulting reduction extraction.