Three-dimensional numerical modelling of a U-Oscillating Water Column array

Abstract

This article proposes the numerical modeling of a plant composed by an array of U-Oscillating Water Columns (U-OWC). The U-OWCs are wave energy converters, commonly embodied in vertical breakwaters, belonging to the family of Oscillating Water Columns. Their particular feature is that they utilize a small vertical duct for connecting the water column to the open wave field. Calculating the system response of these system requires the solution of a system of integro-differential equations involving the determination of the plant hydrodynamic parameters. The article describes the implementation of a numerical model in the ANSYS AQWA® environment. Such a model is used for estimating the radiation damping of the system and its added mass. The numerical results are compared against data based on a semi-analytical approach. It is shown that numerical and analytical models provide similar results, although discrepancies are observed in case of U-OWC with small transversal widths of the openings, due to the different distribution of the pressure field on the U-OWC inlets. However, these differences do not affect significantly the power output estimates.