Numerical and experimental study on hydrodynamic performance of a land-based dual-chamber OWC device under irregular waves

This study examines land-based oscillating water column (OWC) devices numerically and experimentally subjected to the action of regular and irregular waves. The higher-order boundary element method was used to develop the numerical model for the simulation of a single- and dual-chamber OWC. A comparison of the performance of both structures is presented. The JONSWAP spectrum method was employed to generate the irregular waves. Physical experiments were conducted to validate the accuracy of the numerical results and demonstrate the variation of aerodynamic and viscous damping effects in the two device configurations. The dual-chamber configuration is proved to broaden the effective frequency bandwidth. The addition of the internal wall reduces the higher-order wave components inside the chamber. The single-chamber OWC efficiency in irregular wave conditions is approximately 5–12 % lower than in regular wave conditions. The dual-chamber OWC efficiency is reduced at the resonance condition in irregular waves but improved in the low wave-frequency region. It is shown that partial sloshing inside the chambers always occurs under the action of the irregular waves, and this phenomenon is more frequently observed in short period waves. A bottom slope is introduced to enhance the dual-chamber converter peak efficiency in the low-frequency, irregular wave conditions whilst the flat-bottomed OWC demonstrates a wider overall effective frequency bandwidth. The hydrodynamic efficiency of the individual chambers in the OWC is less sensitive to significant wave heights; a finding which contrasts with the case of regular waves.