Hydrodynamic Response of Hybrid FOWC-BBDB Wave Energy Converters Using SPH

To evaluate the longevity and performance of point-absorber wave energy converters (WECs), it is crucial to understand their response to extreme sea conditions. However, data on their hydrodynamic behavior under such stresses is limited. In this study, small-scale experiments using smooth particle hydrodynamics-generated focused waves were performed. These focused waves interacted with a hybrid WEC setup—combining a floating moored oscillating water column (FOWC) and a back-bent duct buoy (BBDB)—and with a point absorber to analyze their mutual effects. Numerical validation against laboratory measurements shows discrepancies in free-surface elevation and pressure of less than 5%, confirming model accuracy. Under hybrid operation, device placement significantly influences efficiency: positioning the system at the front of the wave tank increases the capture width ratio (CWR) by 16.9%, while irregular waves enhance CWR by an additional 7.1% compared to regular waves. Irregular wave conditions generate sway amplitudes up to 40% larger, whereas heave responses of FOWC and BBDB differ by less than 10%. Pitch motions exhibit resonance-driven amplification, reaching 25% above regular-wave levels. Wave-induced forces are dominated by the x-direction component, which exceeds the y-direction component by more than an order of magnitude. The results highlight the enhanced energy capture and dynamic stability of hybrid WEC configurations.