Journal ArticleDOI
Bat Flight Generates Complex Aerodynamic Tracks
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TLDR
It is shown that the wakes of a small bat species differ from those of birds in some important respects, and interpretations of the unsteady aerodynamic performance and function of membranous-winged, flapping flight should change modeling strategies for the study of equivalent natural and engineered flying devices.Abstract:
The flapping flight of animals generates an aerodynamic footprint as a time-varying vortex wake in which the rate of momentum change represents the aerodynamic force. We showed that the wakes of a small bat species differ from those of birds in some important respects. In our bats, each wing generated its own vortex loop. Also, at moderate and high flight speeds, the circulation on the outer (hand) wing and the arm wing differed in sign during the upstroke, resulting in negative lift on the hand wing and positive lift on the arm wing. Our interpretations of the unsteady aerodynamic performance and function of membranous-winged, flapping flight should change modeling strategies for the study of equivalent natural and engineered flying devices.read more
Citations
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Recent progress in flapping wing aerodynamics and aeroelasticity
Wei Shyy,Hikaru Aono,Satish Kumar Chimakurthi,Pat Trizila,Chang-Kwon Kang,Carlos E. S. Cesnik,Hao Liu +6 more
TL;DR: In this article, a review of the recent progress in flapping wing aerodynamics and aeroelasticity is presented, where it is realized that a variation of the Reynolds number (wing sizing, flapping frequency, etc.) leads to a change in the leading edge vortex (LEV) and spanwise flow structures, which impacts the aerodynamic force generation.
Journal ArticleDOI
Closed-Loop Turbulence Control: Progress and Challenges
Steven L. Brunton,Bernd R. Noack +1 more
Journal ArticleDOI
Leading-edge vortex improves lift in slow-flying bats.
Florian T. Muijres,L. C. Johansson,R. Barfield,Marta Wolf,Geoffrey R. Spedding,Anders Hedenström +5 more
TL;DR: Using digital particle image velocimetry, it is shown that a small nectar-feeding bat is able to increase lift by as much as 40% using attached leading-edge vortices during slow forward flight, resulting in a maximum lift coefficient of 4.8.
Aeromechanics of Membrane Wings with Implications for Animal Flight ArnoldSong, ∗ XiaodongTian, † EmilyIsraeli, ‡ RicardoGalvao, § KristinBishop, ¶ SharonSwartz, ∗∗
TL;DR: In this paper, a model for membrane camber due to aerodynamic loading is presented, indicating that the appropriate non-dimensional parameter describing the problem is a Weber number that compares the aerodynamic load to the membrane elasticity.
Journal ArticleDOI
Flapping wing aerodynamics: from insects to vertebrates
Diana D. Chin,David Lentink +1 more
TL;DR: By comparing flapping flight across insects and vertebrates, it is identified how their morphology and kinematics govern both shared and distinct aerodynamic mechanisms, and open research questions in animal flight are highlighted.
References
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Journal ArticleDOI
Flying and swimming animals cruise at a Strouhal number tuned for high power efficiency
TL;DR: Tuning cruise kinematics to optimize St seems to be a general principle of oscillatory lift-based propulsion of swimming and flying animals.
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Aerodynamics of the hovering hummingbird
TL;DR: Measurements of the wake of hovering rufous hummingbirds obtained with digital particle image velocimetry show force asymmetry: hummingbirds produce 75% of their weight support during the downstroke and only 25% during the upstroke, suggesting they may operate at Reynolds numbers sufficiently low to exploit a key mechanism typical of insect hovering.
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A family of vortex wakes generated by a thrush nightingale in free flight in a wind tunnel over its entire natural range of flight speeds
TL;DR: A simple model is formulated and explained that mimics the correct, measured balance of forces in the downstroke- and upstroke-generated wake over the entire range of flight speeds, and might form the basis for a generalisable flight model.