Interplay of elasticity and flow velocity on gorgonian feeding and implications for bioinspired design

Evidence shows that gorgonians are more resistant to ocean acidification and rising temperatures than hard corals and are vital to reef health and the reestablishment of disrupted coral reef communities. Gorgonian coral's resilience and its diversity of morphology and environment make it well-suited as a model organism for bioinspired design applied to particle capture. We focus on flow near the polyps, using an updated form of the immersed boundary method to model the fluid–structure interaction of the flexible polyps and the surrounding ocean water. The inlet velocity and the polyp elasticity are simultaneously varied to gain insight into (1) how these parameters affect the emergent reconfiguration of their tentacles and (2) how the interaction of the reconfiguration and inlet velocity impacts passive particle capture. Two main behaviors are observed: a recirculation regime, in which particles recirculate in a region near the oral disk, and a unidirectional regime, in which the particles move unidirectionally through the tentacles without recirculation. Our results show that different regimes support different feeding strategies. We apply these results as bioinspired filtration, discussing how an elastic material could benefit specific engineering applications.