Computational flow analysis towards understanding the hydrodynamics in a body flexible tuna-like swimming platform*

The Tunabot Flex is a high-performance Tuna-like swimming robot. Numerical simulations are employed to understand the hydrodynamics in the platform, understand the impact of body flexibility, compare to real tuna swimming, and explore design improvements to mimic a real tuna and optimize performance more closely. In this research, high-speed videos of the Tunabot Flex swimming are taken during semi-tethered experiments during forward swimming at varying speeds/frequencies. The motion is then reconstructed digitally by matching frame-by-frame the position of the real platform in the videos with a 3D model. The modeled swimmer is then simulated using an immersed boundary method based direct numerical flow solver. The simulations are used to uncover hydrodynamics and performance in the platform. Comparisons are made with similar simulations of biological tuna swimming and rigid-body versions of the platform. Modeling changes to kinematics, morphology, and frequency of the swimmer are made virtually, enhancing the understanding of the physics and limitations of the platform, as well as inform future design changes in the robot.