Underwater bionic undulating fins incorporating thickness effects: hydrodynamic performance and optimal thickness variation rate analysis

In response to the urgent issues faced by current bionic undulating fin robot propulsion mechanisms, such as low working efficiency, insufficient swimming speed, ignoring thickness parameters, and the need for further improvement in biomimetic degree, this article extends the theory of surface elements to tetrahedral elements using d'Alembert's principle, making it better suited for the research of undulating fins with thickness. By employing computational fluid dynamics simulations and comparative studies, the article examines the influence of motion parameters on the hydrodynamic performance of undulating fins that have thickness. The results are more valuable for engineering applications. Further research on the dimensional parameters of undulating fins is carried out, proposing that the design of undulating fins should theoretically follow the priority order of 'width first, then length, and finally thickness'. Based on this, a bionic fin with variable thickness is designed, and the optimal range of comprehensive hydrodynamic performance for the variable thickness fin is obtained.