Hydrodynamic Study of the Self-Propulsion Performance of an Individual Module in a Modular Underwater Robot with Undulating Fin Propulsion

Considering the advantages of biomimetic undulating fin propulsion, a modular underwater robot was developed, and the linear underwater propulsion performance of its individual module was studied. The CFD method was used to analyze the hydrodynamic characteristics of the robot's underwater self-propulsion, verifying the feasibility of the modular robot's self-propulsion and the overall design's rationality. The variation in speed and thrust of the robot over time during its underwater self-propulsion process was clarified. The transient evolution of the undulating fin, robot and surrounding flow field during the steady-state propulsion cycle was analyzed. A parametric study was conducted to examine the effect of different undulating parameters of the fin on the robot's underwater propulsion performance. The effect of frequency on propulsion performance under different amplitude conditions showed a certain similarity. The effect of amplitude on propulsion performance under different frequency conditions followed the same trend, and when the frequency exceeded 2 Hz, the curve of propulsion performance with respect to amplitude became more similar. The research results provide a theoretical fluid dynamics foundation for undulating fin robot underwater propulsion and also serve as the basis for future research on underwater propulsion in modular reconfigured forms.