Fish body swing and tail vortex structure on maneuverability and agility during C-turn at different curvatures.

This article focuses on the hydrodynamic mechanisms underlying fish turning maneuvers, specifically analyzing how tail vortex structures, body curvature, tail beat frequency, amplitude, and mass influence fish propulsion and motion trajectories. Using numerical simulations of Carangiform swimming, the study finds that asymmetric vortex intensity—quantified by the ratio of positive to negative tail vortices (V1/V2 > 1)—is essential for turning, with curvature being the dominant factor controlling turning radius, maneuverability, and trajectory shape. While increasing tail beat frequency and amplitude enhances turning agility and response speed, their effects on maneuverability and trajectory are limited compared to curvature. Additionally, variations in fish mass affect inertia and response sensitivity but do not alter the fundamental asymmetric vortex distribution driving turning. These insights contribute to understanding fish locomotion and have implications for the design of biomimetic underwater robotics.