Slamming loads induced by dam-break flow on land-based oscillating water columns: Numerical and experimental study

A 3D Reynolds-Averaged Navier-Stokes (RANS) flow solver with a Volume of Fluid (VOF) surface capturing scheme is used to investigate the dam-break flow induced slamming impacts on land-based oscillating water columns (OWC). Comprehensive experiments are conducted to validate the numerical model. It is found that the compressible RANS-VOF solver more accurately captures the key physical processes in this complex fluid- structure interaction process than the incompressible solver. The complete process of dam-break flow impact on OWCs is analyzed in detail, focusing on the relationship between peak forces, moments, slamming pressures, and fluid behaviors. It is found that the peaked vertical loads due to air pressure on the deck of the OWC chamber are non-negligible, particularly for small opening ratios (<3.5%), which has not been previously reported. Additionally, the air pressure on the deck significantly contributes to the moment of the OWC caisson. The distribution of slamming pressure on the front wall, corresponding to peak loading, resembles that of breaking waves in realistic seas. This implies that dam-break flow tests can be used to capture the fundamental physics behind the strong nonlinear waves interacting with OWCs. Numerical simulations are performed to examine the influence of the opening ratio of the OWC chamber on slamming characteristics. It is found that slamming loads on the OWC decrease rapidly with increasing opening ratio in from 0% to 3.5%. However, when the opening ratio exceeds the critical value of 3.5%, the slamming loads change only slightly. Furthermore, during the slamming process, the air pressure inside the chamber is proportional to the velocity of the water surface inside the chamber.