Wave energy extraction by horizontal floating cylinders perpendicular to wave propagation

Abstract

A two-dimensional numerical wave flume is established based on finite element and Volume of Fluid (VOF) methods for incompressible viscous flow. The numerical model is used to simulate waves interacting with single and double horizontal floating cylinders perpendicular to the direction of wave propagation. In the simulations, motion of the floating cylinders, wave forces and wave surface elevations in front of and behind the cylinders are calculated. By applying a damping force on the cylinders to simulate the electrical load, the primary conversion efficiency of wave power is derived. The effect of the cylinders’ cross-sectional size, the normalized damping coefficient for the cylinders’ heave motion, the primary conversion efficiency and the wave transmission coefficient are discussed. This investigation reveals that: larger cylinders are capable of extracting more wave power than smaller ones and also lowering wave transmission; an optimum normalized damping coefficient exists for wave power conversion; when this coefficient increases, heave motions of the cylinders decrease whilst the relative vertical wave force on the cylinders increases; total primary conversion efficiency for double cylinders is higher than that of two separately deployed cylinders due to cylinder-wise interaction.