Vertical Oscillation of a Horizontal Submerged Plate

Many wave energy converter devices consist of an oscillatory body that is connected to an electricity generator. Survivability of the oscillating devices, located on or close to the surface, has been a major difficulty in design of wave energy converters. In addition, the devices are usually located in shallow to intermediate waters, where the interaction of nonlinear shallow water waves with an oscillating object has been a challenging objective for research and development. Here, we propose the use of an oscillatory, horizontal and fully submerged plate, located in shallow water, as the core component of a wave energy converter.

The vertical motion of a fully submerged plate due to nonlinear waves in shallow water is studied here. The nonlinear wave-induced horizontal and vertical forces on the submerged, oscillating plate vary with time and the instantaneous submergence depth, and they are calculated by use of the Level I Green-Naghdi (GN hereafter) equations. Attention is confined to the nonlinear motion of the submerged plate due to waves and other external forces. Effect of the power-takeoff system is simplified by spring and damping forces on the oscillatory plate.