Computational fluid dynamics and experimental study of a model-scale two-body hinged raft wave energy converter

This study presents the validation of a computational fluid dynamics simulation model for a 1:20 scale raft-type wave energy converter subjected to regular incident waves, along with experimental wave tank test results. A damper model in the simulations, calibrated using time-varying damping coefficients, is found to be sufficient to approximate the characteristics of the nonlinear power take-off system. In most test cases, the numerical results correspond appropriately with the model test results, exhibiting a deviations below 10% in terms of capture width ratio, even under steep wave conditions. Stable simulations with steep waves are achieved through an optimized mesh configuration with adaptive refinement. Moreover, variations in device mass and width are identified as key design considerations. Increasing the latter results in higher absorbed power but lower capture width ratio. Flow visualizations are presented in which events with high nonlinearity, such as slamming and overtopping, are identified. These events can contribute to the reduction in power absorption observed in the case of steep waves. • CFD of raft-type WECs agrees well with experiments, even in steep waves. • Time-varying PTO damping captures nonlinear system behavior. • Optimal mesh is proposed for closely spaced raft simulations. • Flow visualizations identified key nonlinear effects. • Sensitivity to mass, center of mass, length, and width is shown.