| Estimating lift from wake velocity data in flapping flight | |
Wang SZ(王士召)1,3 ; He GW(何国威)1,3; Liu TS(刘天舒)1,2
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| Corresponding Author | Liu, Tianshu(tianshu.liu@wmich.edu) |
| Source Publication | JOURNAL OF FLUID MECHANICS
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| 2019-06-10 | |
| Volume | 868Pages:501-537 |
| ISSN | 0022-1120 |
| Abstract | The application of the Kutta-Joukowski (KJ) theorem to estimating the lift of a flying animal based on wake velocity fields often leads to significant underprediction of the lift, which is known as the wake momentum paradox. This work attempts to answer the puzzling question on whether the KJ theorem is legitimate in its use for complex viscous unsteady wakes generated by flapping wings. The limitations in applying the KJ theorem to flapping wings are quantitatively examined through numerical simulations of viscous incompressible flows over three flapping wing models. The three flapping wing models studied in this work are a flapping wing with a fixed wingspan, a flapping wing with a dynamically changing wingspan and a dihedral flapping wing. The KJ theorem fails to give a satisfactory prediction of the time-averaged lift unless an effective span length is correctly computed. We propose a wake-sectional Kutta-Joukowski (WS-KJ) model to predict the time-averaged lift, where the effective span length is computed based on the time-averaged distance between the streamwise vorticity centroids in the right and left half sides of the Trefftz plane. The WS-KJ model incorporates the spatial evolutionary effects of the complex vortex structures in the wake and significantly improves the prediction of the time-averaged lift. The physical foundation for such improvement is explored. In addition, the time-dependent amplitude and phase changes of the unsteady lift are discussed as the fluid acceleration effect. |
| Keyword | swimming/flying |
| DOI | 10.1017/jfm.2019.181 |
| URL | 查看原文 |
| Indexed By | SCI ; EI |
| Language | 英语 |
| WOS ID | WOS:000465309800001 |
| WOS Keyword | AERODYNAMIC FORCE ; ANIMAL FLIGHT ; VORTEX THEORY ; KINEMATICS ; MODEL ; BAT ; DYNAMICS ; THRUST ; POWER ; FLOW |
| WOS Research Area | Mechanics ; Physics |
| WOS Subject | Mechanics ; Physics, Fluids & Plasmas |
| Funding Project | National Natural Science Foundation of China[91752118] ; National Natural Science Foundation of China[11672305] ; National Natural Science Foundation of China[11232011] ; National Natural Science Foundation of China[11572331] ; Strategic Priority Research Programme[XDB22040104] ; Key Research Programme of Frontier Sciences of the Chinese Academy of Sciences[QYZDJ-SSW-SYS002] |
| Funding Organization | National Natural Science Foundation of China ; Strategic Priority Research Programme ; Key Research Programme of Frontier Sciences of the Chinese Academy of Sciences |
| Classification | 一类/力学重要期刊 |
| Ranking | 1 |
| Contributor | Liu, Tianshu |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://dspace.imech.ac.cn/handle/311007/79173 |
| Collection | 非线性力学国家重点实验室 |
| Affiliation | 1.Chinese Acad Sci, Inst Mech, LNM, Beijing 100190, Peoples R China; 2.Western Michigan Univ, Mech & Aerosp Engn, Kalamazoo, MI 49008 USA; 3.Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China |
| Recommended Citation GB/T 7714 | Wang SZ,He GW,Liu TS. Estimating lift from wake velocity data in flapping flight[J]. JOURNAL OF FLUID MECHANICS,2019,868:501-537. |
| APA | 王士召,何国威,&刘天舒.(2019).Estimating lift from wake velocity data in flapping flight.JOURNAL OF FLUID MECHANICS,868,501-537. |
| MLA | 王士召,et al."Estimating lift from wake velocity data in flapping flight".JOURNAL OF FLUID MECHANICS 868(2019):501-537. |
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| Jp2019185.pdf（1958KB） | 期刊论文 | 出版稿 | 开放获取 | CC BY-NC-SA | View Download | |
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