Meeting Abstract
Fish commonly execute rapid linear accelerations initated during steady swimming, and yet linear accelerations are one of the least understood aspects of aquatic propulsion. In this study, we used synchronized ventral and lateral high-speed cameras to examine the linear acceleration of the largemouth bass (Micropterus salmoides). Bass were studied during accelerations from -3.16 to 3.82BL/s2 starting from different steady swimming speeds (1 and 2 BL/s). We observed that the soft-rayed dorsal/anal fins dynamically erect and fold down to change the fin area by more than 70%, and flap side to side within each movement cycle. To better understand the hydrodynamic functions of fin motions during linear acceleration, we implemented a biomimetic undulatory fish robotic model with median fins that include a spine-rayed dorsal fin, soft-rayed dorsal/anal fins, and a caudal fin, which were manufactured using multi-material 3D printing. We used an array of fluidic elastomeric soft actuators to mimic the dorsal/anal inclinator and erector/depressor muscles, which allow the soft fins to erect and fold down and flap laterally. The robotic fish was then mounted to a servo-actuated towing system with programmed speeds that have similar profiles to that of live fish during linear accelerations. A multi-axis force transducer was used to measure three forces and three torques on the robotic model, and DPIV measurements were conducted simultaneously to calculate wake flows. This bio-robotic model could be a promising approach for studying the dynamics of fish swimming behaviors, including linear acceleration, steady swimming, and burst and coast.
