The present study aims at assessing the key spectral parameters of the incident wave on a fixed oscillating water column (OWC) device, based on the air pressure measurements inside the chamber and on the numerical hydrodynamic coefficients of the device.
The methodology is based on the equation of continuity of the air in the time-domain and linear decomposition of the air flow in the usual terms of radiation and diffraction flows. By applying the Fast Fourier Transform, the time-domain equation is transposed to the respective frequency-domain equation.
This methodology was applied to the 400 kW OWC power plant, on the Island of Pico, Azores, which has been monitored since 2005 by the Wave Energy Centre. The numerical hydrodynamic coefficients obtained by the 3D radiation-diffraction boundary element code, AQUADYN-OWC, were used in this study.
No measurements of the incident wave in front of the plant are available; therefore the results obtained for a set of records are compared with forecast estimations for the site of Pico plant provided by INETI and also with the measurements of two directional wave rider buoys offshore Pico and Terceira islands. These data are provided by the Centre of Climate, Meteorology and Global Changes and propagated via the SWAN spectral wave model to the zone of interest.
Final objective is to improve the control of the Pico plant by assessing its performance for a range of sea states.