Experimental investigation on water exchange performance through a hollow buoy driven by wave overtopping

Abstract

A series of regular wave overtopping experiments for a hollow buoy is conducted, and its water exchange behavior is investigated. The variation of its response amplitude, flow rate and net flow rate through the buoy under different wave conditions is analysed. It was found that: 1) The wave height response amplitude in the buoy increases with increasing incident wave period and the incident wave height, respectively. 2) The flow rate through the hollow buoy varies periodically, and its period is consistent with the wave period. The duration of upward flow rate is higher, and its peak value is smaller. In comparison, the duration of downward flow is smaller, and its peak value is higher. 3) For the incident wave period smaller than 2 s, the net flow rate is very small, even it closes to zero; for the incident wave period higher than 2 s, the net flow rate increases obviously, and the water exchange efficiency increases. For a regular wave with higher period and height, the net flow direction is upward. For a regular wave with higher period and smaller height, the net flow direction is downward. The work provides insights to the development and optimization of water exchange device.