Bathymetric wave lenses: enhancing OWC efficiency with parabolic shoals

This study investigates the improvement of Oscillating Water Column (OWC) performance by employing a parabolic shoal to converge wave energy towards the device. Numerical simulations were conducted across a range of wavelengths for circular and rectangular OWC geometries, evaluating key performance metrics. Results show that parabolic shoals can enhance wave energy capture through a combination of depth-induced shoaling and resonance effects. The circular configuration exhibited efficiencies up to three times higher, while the rectangular configuration achieved efficiencies up to 5.5 times higher than the constant water-depth case. The higher performance in the rectangular case was attributed to its greater base efficiency. These findings demonstrate that bathymetric shaping can improve OWC efficiency without mechanical intervention. By concentrating wave energy at the chamber opening, the shoal enables a single OWC to generate the same energy as multiple devices on a flat seabed.