Analysis and optimization of oscillation propulsion performance for flexible pectoral fin

This study aims to uncover the mechanisms underlying swimming posture regulation and to improve the maneuverability of robotic fish. The pectoral fin, as a primary organ responsible for maneuvering, plays a pivotal role in posture control through its characteristic surface oscillation motion. First, the pectoral fin of Labridae was selected as the bionic prototype. A pectoral fin capable of oscillatory motion was designed, and a corresponding motion model was established. Based on this model, wavelength, frequency, and amplitude were identified as key parameters for measuring and regulating the posture of the robotic fish. Next, the hydrodynamic performance of the bionic robotic fish, along with the characteristics of the flow field, was analyzed under different oscillation parameters. Simultaneously, a neural network model was constructed using a computational fluid dynamics dataset, with the motion parameters as inputs and the hydrodynamic performance metrics as outputs. The optimal values—frequency of 2.8684 Hz, amplitude of 0.0993 L, and wavelength of 0.9520 L—were determined with the dual objectives of maximizing thrust and minimizing lift. Finally, experimental results validated the accuracy of the hydrodynamic performance predictions. The numerical simulation method and the verification algorithm provide meaningful theoretical insights for the study of bionic hydrodynamics.