# gst: a flapping forward flight (among Papilio polytes and Kallima inachus)

<< The effect of wing shape on a forward-flying butterfly via decoupled factors of the wing-swept angle and the aspect ratio (AR) was investigated numerically. >>️

<< The results show that, through (AA) models, the effects of the wing-swept angle and AR were decoupled; both have distinct flow mechanisms and aerodynamic force trends and are consistent in the two butterfly species (Papilio polytes and Kallima inachus). For a fixed AR, a backward-swept wing increases lift and drag because of the enhanced attachment of the leading-edge vortex with increased strength of the wingtip vortex and the spanwise flow. For a fixed wing-swept angle, a small AR wing increases lift and decreases drag because of the large region of low pressure downstream and the wake-capture effect. Coupling these effects, the largest lift-to-drag ratio occurs for a forward-swept wing with the smallest AR. These results indicate that, in a flapping forward flight, sweeping a forewing forward relative to a hindwing is suitable for cruising. >>

Sheng-Kai Chang, You-Jun Lin, Kuan-Lun Hsu, and Jing-Tang Yang. Decoupling wing-shape effects of wing-swept angle and aspect ratio on a forward-flying butterfly. Phys. Rev. E 107, 065105. Jun 23, 2023. 

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.107.065105

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Also: vortex in  https://www.inkgmr.net/kwrds.html

Keywords: gst, butterfly, wing, wing-shape, flight, vortex