An integrated simulation approach to study the propulsion mechanism of a biomimetic fishtail

This paper presents an integrated simulation approach to study the propulsion mechanism of a biomimetic silicone fishtail while operating in water. The bending motion of the tail is generated by a cyclic hydraulic water flow that provides a harmonic variation in the inner pressure. A nonlinear finite-element method is employed to obtain the properties of the soft structure; and based on these data, a simplified bar-spring system is created to model the tail. The fluid-structure interaction is handled in the environment of multibody dynamics simulation software which couples the bar-spring system model and an unsteady panel method. Here, the unsteady panel method is used to solve the hydrodynamic problems arising from the complex motion of the fishtail in water. The validations of the bar-spring system model and the unsteady panel method are investigated and confirmed in this paper. The simulation runs for various cases with different values of the hydraulic water pressure and the motion frequency. Based on the propulsion results, it is shown that the present fishtail design is valid for a complete biomimetic fish robot that will be developed soon by the research group. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2021.