Effects of second-order hydrodynamics on the efficiency of a wave energy array

This paper considers power absorption by a square array of four heaving truncated cylinders subject to monochromatic incident waves, where the hydrodynamic calculations are correct to second-order. This idealised WEC array is of particular interest as it supports a near-trapped mode which offers the opportunity for strong hydrodynamic interactions between WECs. However, for typical WEC geometries this mode can only be excited at second-order. The approach taken is to seek to maximise the significance of the second-order effects, though even in a rather extreme case (a near-trapped mode in shallow water) the maximum additional power is approximately 30% of the linear power, while in all other cases the additional power is much smaller