Water wave interaction with a square array of hollow cylinders: Numerical and experimental studies

This study investigates the interaction between water waves and a square arrangement of hollow cylinders. The submerged portion of each hollow cylinder is partially open, which enables the transmission of wave energy into the interior, thereby allowing these structures to function as supports for oscillating water column (OWC) wave energy converters (WECs). Numerical simulations reveal that the amplitude of water-surface oscillation inside the hollow cylinders exhibits a dual-peak characteristic in relation to the changes in wave frequency, which is particularly evident for the downstream hollow cylinders. One of these peaks is closely associated with the resonant piston-mode water-surface oscillation within the cylinders. Additionally, a second significant peak is identified, which corresponds to considerable water-surface oscillation both inside the cylinders and in the external region enclosed by them. In this external region, the characteristics of the wave field closely resemble those of a bottom-mounted vertical cylinder array under the p = 0 trapping mode. To further explore the oscillation characteristic of the water surface inside the hollow cylinders, model experiments have been conducted, confirming the dual-peak phenomenon observed under array conditions and demonstrating notable peak responses that exceed twice the incident wave height. Large-scale WEC arrays can be conceptualized as consisting of multiple square array units, and the insights gained from this study will inform the optimal configuration and hydrodynamic characteristic analysis of extensive WEC arrays.