An Underwater Cylinder‐Enhanced Flag‐Shaped Triboelectric Nanogenerator by Vortex‐Induced Vibration for Low‐Velocity Ocean Current Monitoring

Abstract Accurate ocean flow velocity monitoring is crucial for marine engineering and environmental sensing but faces challenges under low‐flow conditions due to limited energy, power integration difficulties, and reduced sensor sensitivity. To overcome these, this work introduces a novel underwater cylinder‐enhanced flag‐shaped triboelectric nanogenerator (UCF‐TENG). It utilizes vortex‐induced vibrations (VIV) from an upstream bluff body for efficient flow detection. Based on a quantified Strouhal number relationship, the UCF‐TENG provides a direct, linear mapping between flow velocity and output signal frequency. Experimental results demonstrate that the UCF‐TENG achieves a startup flow velocity as low as 0.211 m·s −1 and a peak output voltage of 1.81 V. Across the tested velocity range, the output signal frequency maintains a strong linear correlation with flow velocity (R 2 = 0.9893), indicating excellent sensitivity under low‐flow conditions. Furthermore, fluid‐structure interaction (FSI) simulations conducted in ANSYS Fluent validate the underlying VIV‐driven signal generation mechanism and provide theoretical support consistent with experimental observations. This work offers a compelling solution for real‐time, energy‐autonomous flow sensing in resource‐constrained marine environments and holds application prospects in intelligent marine systems.