In this paper, we carried out a numerical investigation of the hydrodynamic performance of a floating pendulum wave energy converter (WEC). This movable-body-type device consists of three main parts: floater, pendulum and damping plate. The performance of the WEC device was evaluated under regular and irregular wave conditions using frequency-domain floating body dynamics. In this study, the higher-order boundary element method (HOBEM) based on potential flow model was applied to obtain the hydrodynamic coefficients and wave exciting forces acting on floating bodies. The hinged motion of the pendulum was simulated by applying the penalty method. In order to avoid an unrealistic resonant response, numerical body damping was adopted. The coupled dynamics of floater and pendulum were analyzed as a hinged multi-body model. First, the wave force and motion characteristics of the device in regular waves were studied. Then, the performance of the WEC device was evaluated under irregular wave conditions. The effects of the main shape parameters on power absorption and floater motion were numerically investigated.
Many kinds of wave energy converter (WEC) have been proposed recently. They can be categorized as one of three basic types: an oscillating-water-column (OWC) type, a wave overtopping type and a movable-body type. The oscillating-water-column types use the airflow induced by wave motion to generate power via an air turbine, whereas the overtopping type makes use of the potential energy of overtopping water via a water turbine. However, movable-body WECs adopt a direct energy transfer system, whereby the translation and rotational motion of an incoming wave directly induces mechanical motion of the power generator. Among the three types of converter, the movable-body type is known to be the most efficient device. However, the movable-body WEC device is vulnerable to structural damage, because the device is directly exposed to harsh environmental loads.