Document Type

Article

Publication Date

7-8-2026

Abstract

Flapping-wing flight is inherently unsteady, where atmospheric gusts can substantially degrade the aerodynamic performance when their characteristic time scales are comparable to the wingbeat period. This study presents a numerical investigation and time–frequency characterization of gust-induced aerodynamic response of flapping wings of varying size, inspired by the flight of a longhorn beetle, Batocera rufomaculata. Geometrically similar wings spanning the biological range were simulated in forward flight under identical prescribed kinematics and a transient frontal gust with a smoothly ramped profile. Three-dimensional unsteady Reynolds-averaged Navier–Stokes simulations using the shear stress transport k–ω turbulence model were performed to resolve the instantaneous pressure field and three-dimensional vortex structures. The Q-criterion, pressure coefficient, and turbulent kinetic energy were analyzed to relate coherent vortices, turbulence production, and load fluctuations. Aerodynamic response was quantified using lift, pitching moment, and lift-to-drag ratio, while gust sensitivity and recovery were assessed through transient deviations and post-gust settling behavior. Time–frequency analysis of the non-stationary lift signal was used to track how gust forcing redistributed spectral content across the fundamental flapping frequency, its harmonics, and broadband components associated with vortex breakdown and flow reorganization. The results showed that gusts did not simply scale aerodynamic loads; rather, they transiently modified effective angle of attack and vortex topology, producing size-dependent differences in load amplification, turbulence redistribution, and recovery. Larger wings exhibited greater susceptibility to gust-induced loading and returned more slowly to pre-gust aerodynamic performance.

This article was published Open Access through the CCU Libraries Open Access Publishing Fund. The article was first published in Physics of Fluids: https://doi.org/10.1063/5.0334612

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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