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- Experimental study of an onshore dual chamber oscillating water column devicePublication . Gadelho, Jorge; Rezanejad, Kourosh; Guedes Soares, Carlos; Santos, João Alfredo; Anastas, Gael; Fortes, ConceiçãoA wave flume is used to study a scaled model of a stepped bottom dual-chamber Oscillating Water Column (OWC) installed onshore. Compared to traditional single-chamber OWCs, the use of dual-chambers is expected to widen the range of sea states in which the OWC is more efficient, and the step, in front of the first chamber, boosts the capturing energy capacity of the device. The Power Take-Off (PTO) system is modelled as an air opening in the pneumatic chambers. Several experiments combining regular incident waves and PTO damping conditions are performed. Results of the amplitudes of the free surface elevations inside the chambers show that the device can amplify the incident wave amplitude up to 1.57 times in chamber 2. Results of the primary ef ficiency show that the device is highly dependent on the PTO damping characteristics and can reach around 40% for a wide range of wave periods. Results of the reflection analysis show that the reflection coefficient is also dependent on the PTO damping characteristics but remain lower than 0.6 for all the studied cases. Sloshing phenomenon (mostly in the cross-section direction) was observed for a wavelength close to the cross-section dimension, impacting negatively on the device pneumatic performance.
- Numerical and experimental study of ship-generated wavesPublication . Rodrigues, Sara; Guedes Soares, Carlos; Santos, João AlfredoThis paper presents the results of the numerical and experimental study on the propagation of ship-generated waves. In the numerical modified FUNWAVE code, which is able to reproduce most of the phenomena involved in wave propagation, the ship is represented by a moving pressure distribution function at the free surface. The experimental tests were carried out with a ship model at a 1: 50 scale that moving at constant speed across a constant depth region. The values of wave heights obtained in the scale ship model 1: 50 were used to compare with the predictions of wave heights provided by the numerical code. The comparison of the results obtained by the numerical code and the experimental tests shows very similar values for the maximum wave height.