![]() ![]() For constant flow conditions, the vortices are directed gently across the oral arms where particle capture occurs. ![]() The results show that the oral arms trap vortices as they form during contraction and expansion of the bell. The elaborate oral arm structure is modeled as a homogenous porous layer. In this paper, the immersed boundary method is used to simulate a simplified jellyfish in flow. Flow velocities and directions fluctuate on multiple time scales, and mechanisms of particle capture may be fundamentally different in moving fluids. All of this work, however, has considered the jellyfish in the absence of background flow, but the natural environments of Cassiopea and other cnidarians are dynamic. Previous experiments and numerical simulations have shown that the oral arms play an important role in directing new fluid into the bell from along the substrate. The upside-down jellyfish ( Cassiopea spp.) is an ideal organism for examining feeding and exchange currents generated by bell pulsations due to its relatively sessile nature. The effects of varying bell diameter on pore water release and pumping currents will be discussed.įeeding currents of the upside down jellyfish in the presence of background flow. 2D particle image velocimetry (PIV) measurements were conducted on the same individuals to correlate PLIF-based concentration profiles with the jets generated by pulsing of medusae. Planar laser-induced fluorescence (PLIF) measurements were conducted to visualize the release of pore water via bell motion, using fluorescent dye introduced underneath the substrate. The goal of this study is to examine pore water pumping by Cassiopea individuals in laboratory aquaria, as a model for understanding pore water pumping in unsteady flows. Their pulsations have also been proposed to generate forces that can release sediment locked nutrients into the surrounding water. Pulsations of their bells are used to generate currents for suspension feeding. These medusae exhibit a sessile, non-swimming lifestyle, and are oriented such that their bells are attached to the substrate and oral arms point towards sunlight. Patchy aggregations of Cassiopea medusae, commonly called upside-down jellyfish, are found in sheltered marine environments with low-speed ambient flows. Gaddam, Manikantam Santhanakrishnan, Arvind Pore Water Pumping by Upside-Down Jellyfish ![]()
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