Abstract: A complete study of a WEC, from the design of the WEC to the numerical modelling and experimental simulations, is presented in this work. The WEC under study is composed of two bodies, one floating body with a circular shaped deck where a second body, the rotor, moves rotating like a pendulum in angles between, -45o and 45o. The energy extraction is done through the relative rotation between the floating body in roll, and the rotation of the rotor, _. In order to avoid the restriction of roll movements, the WEC is connected, by a catenary, to a moored buoy. The numerical model used is a time domain model based in linear potential theory through Cummin's equation. The model modifies inertia and hydrostatic matrices, which depend on the relative position of both bodies, in order to consider large tilts of the floating body and movements of the rotor. The model considers the DOFs of sway, heave and roll. The rotor movements' equations are included together with the DOFs obtaining a system of 4 second order differential equations where the coefficients of the matrices change every time step. The quasistatic model is used to study the mooring system employed in the laboratory tests. Laboratory experiments to characterize the WEC and regular and irregular wave trains wave trains were performed. The natural period of the WEC in roll is 7.5 seconds. The results of the numerical model are compared with those at the lab for decay test of heave and roll with fixed and moving rotor, and regular waves. The results of the numerical model showed a good agreement, in general, with those obtained at the laboratory.

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