Meeting Abstract

17.1  Wednesday, Jan. 4  Numerical simulations and laboratory experiments of the upside-down jellyfish with background flow HAMLET, C. L.*; MILLER, L. A.; North Carolina State University ; University of North Carolina at Chapel Hill

The upside-down jellyfish (Cassiopea spp.) is an ideal organism for examining the effects of jellyfish kinematics on the flow of the surrounding fluid due to its relatively sessile nature. Previous experiments and numerical simulations have shown that the secondary structures such as the oral arms play an important role in directing flow around the bell from the substrate. Here we present laboratory experiments and numerical simulations that examine the interaction of the effects from ambient flow and the pulsation of the bell. Dye visualization and PIV techniques are used to observe the fluid flow around laboratory specimens. The immersed boundary method is used to numerically solve the fluid structure interaction problem for an idealized two-dimensional organism. Of particular interest is the influence of the speed and direction of the ambient flow as well as the effect of the presence of a secondary structure in the general region of the oral arms structure. We show that at low velocities the secondary structures direct flow across feeding regions. In addition for variable directional flows, the secondary structure change the overall structure and direction of the flow around the bell. Implications of these effects on particle exchange and feeding will be explored.