Bio-inspired piezoelectric scales for active turbulent drag reduction

Existing bionic scale drag reduction technologies primarily mimic the morphology and arrangement patterns of fish scales to achieve drag reduction, but fail to replicate the active micro-vibrations of scales. This study develops a bio-inspired scale system based on piezoelectric actuation, where the piezoelectric actuator serves as the active vibration component to drive the scales and generate coupled perturbations within the boundary layer. This study advances biomimicry from static geometry to dynamic function. The design biomimics the morphological architecture of fish scales while replicating their microscale kinematic flow control mechanisms, achieving viscous drag mitigation through dynamic boundary layer modulation. Through simulation analysis, the drag reduction mechanism of the drag reducer was revealed, and proposed drag reduction performance control method. Drag reduction experiments were conducted to validate the effectiveness of the reducer, which demonstrate that the proposed bionic piezoelectric scale reducer effectively reduces wall frictional drag. The drag reduction rate of the drag reducer can reach 24.13 % at an incentive amplitude of 100 V and an operating frequency of 1648 Hz. This work can provide insights for advancing bionic scale drag reduction technologies.