Fluid-Structure Interaction study on a flexible robotic pectoral fin

Interested by the phenomenon that flexible structures of living creatures have better performance than the artificial rigid propeller, a study on Fluid-Structure Interaction (FSI), which solves the coupling between solid structure and fluid, is conducted to investigate the stiffness effect of the pectoral fin. Firstly, a three dimension computational fin model based on the pectoral fin of Koi Carp is adopted and three cases are investigated which are rigid case, flexible case and flexible variable stiffness case, respectively. With this approach, their hydrodynamic force and fluid field are compared, and it is discovered that flexible cases have better hydrodynamic force and special fluid field, and there is a delay-response in the flexible structure. The flexible variable stiffness case exhibits the best performance in our experiment. Moreover, corresponding robotic pectoral fin experiments are carried out and the results Coincide with those of the simulation. The results will be a useful inspiration for the design of flexible underwater propeller and understanding of fish swimming mechanism.