Meeting Abstract

81.5  Sunday, Jan. 6  To Pause or Not to Pause: Effects of Pauses and Grouping on Fluid Flow around the Bell of the Upside-Down Jellyfish, Cassiopea spp. HAMLET, C. L.*; MILLER, L. A.; RODRIGUEZ, T.; Tulane University; University of North Carolina at Chapel Hill; University of California Berkeley chamlet@tulane.edu

The sessile nature of the upside-down jellyfish Cassiopea spp. makes it an ideal organism for gathering large sets of data on the kinematics of bell pulsations. Previous experiments and simulations have demonstrated the important role secondary structures play in directing flow around the bell. Here we present numerical simulations examining the effects of pulse timing and of spacing between organisms. We develop a discrete time Markov chain model based on pulse patterns of laboratory specimens to drive the bell kinematics. Effects of observed grouping of similar size and of different size specimens are explored in conjunction with the Markov chain model. Immersed boundary methods are used to solve the resulting coupled fluid-structure interaction problem. Our preliminary results show that variability of pauses between muscle contractions result in very different bulk flow patterns around the bell with implications for particle capture and exchange efficiency. Simulations of paired jellyfish indicate grouping has the potential to enhance opportunity for particle sampling, particularly for smaller specimens.