Effect of morphological characteristics on the aerodynamic performance of a flexible flapping butterfly wing

Flapping-wing micro aerial vehicles (FWMAVs) inspired by insects like butterflies offer exceptional maneuverability, yet the coupled effects of wing morphology and structural flexibility on their aerodynamics remain underexplored. This study employs a high-fidelity fluid–structure interaction (FSI) framework to simulate the flapping motion of a bioinspired Chilasa clytia butterfly wing. We systematically investigate the influence of key morphological characteristics, particularly the angle between forewing and hindwing (Δα=+20°,0°,−20°,−40°), and wing flexural stiffness (E=3,4,5,6,10 GPa) on its unsteady aerodynamic performance and vortex dynamics. Results demonstrate that the baseline wing morphology (Δα=0°) achieves superior overall aerodynamic performance across all conditions. Flexible wings (E=4 GPa) significantly outperform rigid wings, generating 50.65% higher lift peaks due to complex vortex structures like the wingtip secondary flow vortex and hind tip vortex, which create additional low-pressure regions. The baseline wing morphology (Δα=0°) with a flexural stiffness of E=4 GPa is identified as the optimal configuration under the conditions considered, striking the best balance between lift generation, thrust production, power consumption, and overall propulsive efficiency. This work elucidates the critical interplay between morphology and flexibility in butterfly flapping-wing aerodynamics, providing valuable insight for the design of high-performance bio-inspired FWMAVs.