Dynamic suspension feeding in sheet-like soft coral colonies

The morphology, arrangement, and material properties of filtering structures play a significant role in the suspension feeding of corals. Unlike hard corals, soft corals such as sea fans can leverage structural flexibility to reconfigure their entire colony when exposed to varying flow conditions. Though flow-induced reconfiguration reduces drag and prevents dislodgement, its implications on suspended particle capture remain unclear. Previous studies have been limited to unidirectional flows, where particle capture occurs primarily at the upstream-facing surface. This study examines particle capture by sheet-like sea fans in the presence of wavy flows, such as those observed during storm surges. 2D PIV measurements and CFD simulations were conducted on physical and numerical models of a sea fan (G. ventalina). The models were subject to varying oscillation parameters while being exposed to a continuous, mean background flow. The findings indicate that the sweep area exhibited by the sea fan, determined by the oscillatory amplitude and whole colony flexibility, plays a significant role in particle dynamics, redistribution, and capture.