Beneficial wake-capture effect for forward propulsion with a restrained wing-pitch motion of a butterfly.

ABSTRACT: Unlike other insects, a butterfly uses a small amplitude of the wing-pitch motion for flight. From an analysis of the dynamics of real flying butterflies, we show that the restrained amplitude of the wing-pitch motion enhances the wake-capture effect so as to enhance forward propulsion. A numerical simulation refined with experimental data shows that, for a small amplitude of the wing-pitch motion, the shed vortex generated in the downstroke induces air in the wake region to flow towards the wings. This condition enables a butterfly to capture an induced flow and to acquire an additional forward propulsion, which accounts for more than 47% of the thrust generation. When the amplitude of the wing-pitch motion exceeds 45°, the flow induced by the shed vortex drifts away from the wings; it at

SUBMITTER: Lin YJ 

PROVIDER: S-EPMC8385355 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature