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Title: Aerodynamic performance of a free-flying dragonfly—A span-resolved investigation
Authors: Hefler, C.
Noda, R.
Qiu, H. H.
Shyy, W.
Author's alias: 野田, 龍介
Issue Date: Apr-2020
Publisher: AIP Publishing
Journal title: Physics of Fluids
Volume: 32
Issue: 4
Thesis number: 041903
Abstract: We present a quantitative characterization of the unsteady aerodynamic features of a live, free-flying dragonfly under a well-established flight condition. In particular, our investigations cover the span-wise features of vortex interactions between the fore- and hind-pairs of wings that could be a distinctive feature of a high aspect ratio tandem flapping wing pair. Flapping kinematics and dynamic wing-shape deformation of a dragonfly were measured by tracking painted landmarks on the wings. Using it as the input, computational fluid dynamics analyses were conducted, complemented with time-resolved particle image velocimetry flow measurements to better understand the aerodynamics associated with a dragonfly. The results show that the flow structures around hindwing’s inner region are influenced by forewing’s leading edge vortex, while those around hindwing’s outer region are more influenced by forewing’s shed trailing edge vortex. Using a span-resolved approach, we found that the forewing–hindwing interactions affect the horizontal force (thrust) generation of the hindwing most prominently and the modulation of the force generation is distributed evenly around the midspan. Compared to operating in isolation, the thrust of the hindwing is largely increased during upstroke, albeit the drag is also slightly increased during the downstroke. The vertical force generation is moderately affected by the forewing–hindwing interactions and the modulation takes place in the outer 40% of the hindwing span during the downstroke and in the inner 60% of the span during the upstroke.
Rights: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Physics of Fluids 32, 041903 (2020) and may be found at https://doi.org/10.1063/1.5145199.
The full-text file will be made open to the public on 15 April 2021 in accordance with publisher's 'Terms and Conditions for Self-Archiving'.
URI: http://hdl.handle.net/2433/252323
DOI(Published Version): 10.1063/1.5145199
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