Modeling of an ocean waves power device AWS

This paper describes the steps for building the time domain model of an ocean waves energy converter device called AWS (Archimedes wave swing). This model is useful for the design of such devices and for the prediction of its behavior in different sea conditions. Besides the inherent complexity associated to the nonlinear dynamics of the AWS components, for time domain simulation, a convolution integral is conventionally used to model the hydrodynamic diffraction and radiation forces, being the last one characterized in the frequency domain by the added mass and damping. However, this integral is relatively expensive to evaluate and difficult to use with efficient integration routines. Here, an efficient methodology mixing frequency-and time-domains is introduced to deal with this problem. The wave transfer functions were first obtained from a numerical finite element code, as vectors containing the frequency response of the desired transfer functions. The data obtained is then used to identify the corresponding analytic form of the transfer functions, which is integrated in the time-domain model. The model includes the slow and fast dynamics of the AWS behavior.