Physical modeling of Mastigias papua feeding structures and simulation of their effect on bell stress and kinematics

This study reports the progress made towards understanding of the low energy propulsion mechanism of medusae (jellyfish) for developing energy efficient unmanned underwater vehicles (UUV). The focus of this investigation is on identifying the techniques required for prolonged sustainability of UUVs. Inspiration is taken from the constant feeding and energy generation achieved by Rhizostomeae. Rhizostomeae, in particular, utilize oral structures comprised of internal channels that capture zooplankton entrained in flow surrounding and in the wake of jellyfish on distal capture surfaces. A passive model was generated for the capture surfaces utilizing the physical dimensions based upon the morphology of Mastigias papua with a bell diameter of 17.2 cm. Geometry and structure of the oral components were derived from literature, live samples, and digitization of video. Based upon this data, a mold was created using silicone and assembled to achieve jellyfish inspired architecture. Geometries used to create the passive model were input into a Finite Element Analysis (FEA) simulation along with the experimental material properties of jellyfish mesoglea to ascertain the affect that the oral structure has on the kinematics and bell stresses. A forcing function was derived to achieve a close approximation of the jellyfish kinematics for the case of a jellyfish bell with oral structure attached. The same forcing function was applied to the singular bell and an increase in the bending was observed. With the escalation in bending came an increased level of principle stress within the bell closer to the margin. From this the stiffness elements that must be compensated with increased actuation force applied to the bell achieving proper swimming kinematics can be identified.