https://scholars.lib.ntu.edu.tw/handle/123456789/598057
標題: | Beneficial wake-capture effect for forward propulsion with a restrained wing-pitch motion of a butterfly | 作者: | Lin Y.-J Chang S.-K Lai Y.-H Yang J.-T. JING-TANG YANG |
關鍵字: | Butterfly flight;Forward propulsion;Induced flow;Wake-capture effect;Wing-pitch motion | 公開日期: | 2021 | 卷: | 8 | 期: | 8 | 來源出版物: | Royal Society Open Science | 摘要: | 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 attenuates the wake-capture effect and causes the butterfly to lose a part of its forward propulsion. Our results provide one essential aerodynamic feature for a butterfly to adopt a small amplitude of the wing-pitch motion to enhance the wake-capture effect and forward propulsion. This work clarifies the variation of the flow field correlated with the wing-pitch motion, which is useful in the design of wing kinematics of a micro-aerial vehicle. ? 2021 The Authors. |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114632847&doi=10.1098%2frsos.202172&partnerID=40&md5=e6442224f8122bdfb5614d3cc2a9d5d6 https://scholars.lib.ntu.edu.tw/handle/123456789/598057 |
ISSN: | 20545703 | DOI: | 10.1098/rsos.202172 |
顯示於: | 機械工程學系 |
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