Bioinspired morphing offers a powerful route to higher aerodynamic and hydrodynamic efficiency. Birds reposition feathers, bats extend compliant membrane wings, and fish modulate fin stiffness, tailoring lift, drag, and thrust in real time. To capture these advantages, engineers are developing airfoils, rotor blades, and hydrofoils that actively change shape, reducing drag, improving maneuverability, and harvesting energy from unsteady flows. This review surveys over 296 studies, with primary emphasis on literature published between 2015 and 2025, distilling four biological archetypes—avian wing morphing, bat-wing elasticity, fish-fin compliance, and tubercled marine flippers—and tracing their translation into morphing aircraft, ornithopters, rotorcraft, unmanned aerial vehicles, and tidal or wave-energy converters. We compare experimental demonstrations and numerical simulations, identify consensus performance gains (up to 30% increase in lift-to-drag ratio, 4 dB noise reduction, and 15% boost in propulsive or power-capture efficiency), and analyze materials, actuation, control strategies, certification, and durability as the main barriers to deployment. Advances in multifunctional composites, electroactive polymers, and model-based adaptive control have moved prototypes from laboratory proof-of-concept toward field testing. Continued collaboration among biology, materials science, control engineering, and fluid dynamics is essential to unlock robust, scalable morphing technologies that meet future efficiency and sustainability targets.

In this study, we investigated the power generation capability of an oscillating wing energy harvester featuring an actively controlled flap positioned at the wing’s leading edge. The findings revealed that attaching a leading-edge flap reduces fluid flow separation below the wing’s lower surface at the leading edge, resulting in smoother flow and increased velocity near the hinge region. The leading-edge flap increases the pressure difference across the wing’s surface, thereby enhancing the overall performance. In addition, the introduction of the leading-edge flap effectively elongates the wing’s effective projected length in the heaving direction, leading to increased thrust. We examined flap lengths ranging from 10% to 50% of the chord length, with the maximum pitch angles of the wing and flap varying from 75° to 105° and 30° to 55°, respectively. The optimal power generation was achieved using a flap length of 40% of the chord length, combined with maximum wing and flap pitch angles of 95° and 45°, respectively. These conditions yielded a 29.9% overall power output increase and a 20.2% efficiency improvement compared to the case without the leading-edge flap.

Flapping-foil energy harvesters represent a promising technology for extracting energy from fluid flows, although their performance under shear-flow conditions is poorly understood. To address this research gap, we investigated the impact of power-law shear flow on the performance of flapping-foil energy harvesters. We conducted numerical simulations at different Reynolds numbers (Re = 1000, 50 000, and 500 000) under uniform-flow and shear-flow conditions. Based on the results, shear flow minimally affected the power outputs at Re = 1000 and 50 000, where viscous forces dominate the flow dynamics. However, at Re = 500 000, shear flow significantly reduced the power output, by up to 10% relative to uniform flow, primarily due to alterations in the vortex shedding and pressure distributions resulting from the velocity gradient. Additionally, we considered variations in the heaving amplitude and found that although this parameter has minimal effect at low Reynolds numbers, it is critical at Re = 500 000. Specifically, the performance disparity between uniform and shear flows was pronounced at low amplitudes. These findings highlight the importance of considering shear-flow effects and optimizing the heaving amplitude to maximize the performance of flapping-foil energy harvesters in realistic fluid environments.

This study investigates the impact of different duct designs on the energy-harvesting performance of oscillating-wing systems in both partially and fully confined environments. Numerical simulations were conducted to examine the effects of straight, convergent–straight, and convergent–divergent duct configurations on the aerodynamic forces and overall energy extraction efficiency. Under partial confinement, the convergent–divergent duct demonstrated a significant improvement of 67.5% in power output over the ductless baseline configuration. This enhancement is attributed to the increased incoming flow velocity and amplified pressure difference around the wing, which improve the effectiveness of energy generation. However, the straight and convergent–straight ducts reduced the harvester’s performance due to the diminished flow velocity within each duct. Under full confinement, all duct configurations substantially enhanced energy-harvesting performance, with the convergent–straight duct providing the highest efficiency gain (84.9%). This improvement is primarily due to the increased velocity and pressure differential across the wing surfaces, which maximise the heaving force and overall energy generation performance. These findings highlight the critical role of duct geometry in optimising energy-harvesting performance, both in partially confined and fully confined flow environments.