Abstract
Since wave energy conversion systems, with hydrodynamic bodies and power take-off components, exhibit nonlinear behavior and operate under stochastic sea-states, sensitivity analysis provides a more computationally tractable approach than optimization for evaluating design parameters. We conducted a Taguchi-based sensitivity analysis to examine how flap geometry, density, and power take-off parameters influence mechanical power extraction in Oscillating Surge Wave Energy Converters (OSWECs). Four design parameters-flap shape (rectangular to trapezoidal), density (100–400 kg/m3), PTO stiffness (0–200 Nm/rad), and PTO damping (10–300 Nms/rad)- were systematically varied using a 16-run Taguchi array. The analysis incorporated hydrodynamic coefficient calculation using Capytaine coupled with time-domain simulations in WEC-Sim, under wave conditions derived from the PacWave South testing facility. To validate the Taguchi trends and to provide physical insight, we conducted a frequency-domain, one-degree-of-freedom equation-of-motion analysis. This clarified fundamental differences between point absorbers and OSWECs, linking the Taguchi findings to OSWEC's excitation-driven performance rather than resonance. PTO damping emerged as the primary driver of mechanical power extraction, whereas changes in flap geometry, density, and PTO stiffness had negligible influence within the tested ranges. These results suggest that OSWEC design should focus on tuning PTO damping while maintaining simple rectangular flap shapes, rather than modifying the geometry to match natural frequencies-effective for point absorbers but not amenable to OSWECs.