A numerical-experimental study on the hydrodynamic performance of a U-OWC wave energy converter

The present work is aimed to the formulation of empirical relationships useful for the design of a U-OWC type marine energy conversion device, with particular reference to the calculation of the resonance index and hy-drodynamic efficiency. The study was conducted using physical and numerical modelling.The experimental campaign was carried out within the flume at the Hydraulics Laboratory of the University of Messina. Tests were performed by forcing the model on a scale of 1:30 with the action of several regular waves and varying the geometry of the device. Furthermore, to extend the experimental dataset with more energetic waves and new geometrical characteristics, the physical model was also reproduced numerically using the CFD software OpenFOAM. The validation process of the numerical model showed that the turbulent LES model reproduced the behaviour of the device more effectively than the turbulent Kappa-omega SST model, particularly for the more energetic waves. The extended dataset (experimental and numerical) was analysed by discussing the dependents of the hy-draulic and energetic performance concerning the orifice diameter of the device and the width of the U-OWC vertical duct. It was observed that the combination of such geometrical characteristics resulted in an enhanced effect regarding the performance of the device, particularly the energy performance.