Wave energy harvesting and motion mitigation of floating structures via oscillating water column devices

A floating structure integrated with dual oscillating water column (OWC) wave energy converters is numerically investigated using OpenFOAM and waves2Foam to explore its potential for simultaneous wave energy harvesting and motion mitigation. The volume of fluid method for interface capturing, the six-degree-of-freedom dynamic mesh solver waveDyFoam for motion responses and the porous media layer method for power take-off (PTO) damping are adopted to systematically analyze the influence of OWCs' relative chamber width, wall draft depth, and PTO settings on integrated floating structure's motion suppression and energy capture performance under regular waves. The results show that integrating dual OWC devices substantially alters the peak values of the floating structure's motions while shifting the resonant frequency. Optimal pitch motion suppression in the investigated cases occurs at a relative chamber width of 1/6, relative wall draft depth of 1/1, and PTO orifice ratio of e = 0.25%, achieving amplitude reductions of 63.68%, 63.68%, and 80.61%, respectively. A larger chamber width and smaller wall draft depth enhance wave energy conversion efficiency, notably broadening the high-efficiency frequency bandwidth. The optimal energy conversion efficiency is highly sensitive to PTO parameters, with the configuration e = 0.5% yielding the best performance. Transient flow field analysis elucidates the evolution of the floating structure's dynamic response.