Simulations of Pulsing Soft Corals

Sessile soft corals in the Xeniidae family actively pulse their tentacles and are one of the few known species to move in such an energetically expensive way for a purpose other than locomotion. This pulsing was first thought to facilitate food capture, however they are rarely found with food in their gastric cavity. Instead experimental work has hypothesized that the pulsing mixes the surrounding fluid to increase the rate of photosynthesis, by up to an order of magnitude, for their symbiotic algae that provide the corals with energy. The pulsing of the corals and resulting fluid flow are modeled in three dimensions using the immersed boundary method and by solving the Navier-Stokes equations for the incompressible flow velocity and pressure, using the open-source software IBFE. Using two-dimensional slices of simulated velocity fields, we seek to understand how the coral motion affects the fluid mixing. Preliminary results will be presented.