Wave power absorption by a metamaterial cylinder with internal paddle power take-off system

In this paper, a novel type of wave energy converter is considered. Thin vertical parallel plates extending through the depth are confined to a vertical cylinder and the fluid in the narrow channels is excited at the cylindrical boundary by plane incident waves. Each narrow channel is divided into two unconnected fluid domains along its centreplane by a pair of opposing paddles, hinged below the surface and attached to springs and dampers through which useful energy is harvested. The problem is simplified by introducing a continuum approximation which replaces the effect of the narrow channels by an effective medium equation and considers the displacement of the two opposing rows of discrete paddles as two continuous functions of the position. This allows the development of a solution by separation of variables which is simple to implement and efficient to compute. The results provide some surprising results, including the capacity to generate power well in excess of an equivalent cylindrical device operating in rigid body motion and without introducing large unphysical amplitudes in the paddle displacement or the wave field. We also show that the power generated by this wave energy converter is relatively insensitive to the incident wave heading. Some optimisation is performed to show the maximum power harvesting potential of the proposed device.