Computational analysis of underlip geometry and power take-off damping effects on oscillating water column performance

The geometry of the underlip in onshore oscillating water column (OWC) systems is a key determinant of their hydrodynamic performance, directly influencing the wave-structure interactions and energy conversion efficiency. Recent advances in experimental hydrodynamics have highlighted the potential of geometric optimization; however, the specific influence of underlip configurations remains underexplored in the context of high-fidelity computational modeling. This study addresses this gap by performing a systematic evaluation of multiple underlip geometries using computational fluid dynamics (CFD) simulations. The analysis revealed that subtle geometric modifications could yield substantial performance gains. Notably, the circular underlip configuration achieved the highest improvement, enhancing the efficiency by 9.1% under a takeoff damping variation of 0.0079. This improvement was attributed to its capacity to suppress turbulent kinetic energy generation during wave impact, thereby reducing energy dissipation. The results present a novel, cost-effective design optimization pathway that requires minimal structural modification, contributing to the growing body of research on hydrodynamic enhancement strategies for OWC-based wave energy converters.