ON THE TIME-VARIABILITY OF ADDED MASS AND DAMPING OF A FLAP TYPE WAVE ENERGY CONVERTER

Almost most of mathematical models of fluid-body interaction represent the radiation effect as two frequency dependent components proportional to acceleration andvelocity. This approach originally comes from strip theory of ship motions [1]. Mathematical models for simulating body motion also suggest to include another damping term proportional to a higher power of velocity [2], for fluid-body interaction, it could compensate the nonlinearities and viscous effects [3]. In this paper, radiation damping, added mass and the quadratic damping coefficient are extracted from the free decay experimental results. Different approaches have been used for extracting these parameters, based on the stages of time dependency. The parameters are used to investigate the ability and applicability of the abovementioned models for simulation of a flap type wave energy converter, patented by [4]. The numerical results will be compared with the experimental measurements. It will be shown that due to the rapid motions of this device and the interactions between flaps in an array, considering constant damping and added mass could not effectively model themotion of this type of wave energy converter.