Passive dynamics regulates aperiodic transitions in flapping wing systems
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Published version
Author(s)
Majumdar, Dipanjan
Ravi, Sridhar
Sarkar, Sunetra
Type
Journal Article
Abstract
Natural and artificial flapping wing flyers generally do not exhibit chaos or aperiodic dynamic modes, though several experimental and numerical studies with canonical models of flapping foils have reported inevitable chaotic transition at high ranges of dynamic plunge velocity (κh
). Here we considered the idealized case of a pitching–plunging flapping foil and numerically investigated the effects of passive pitching dynamics on the fluid forces and dynamical states, and compared it with a fully actuated wing. We found that in comparison to fully actuated foils, aperiodic transition can be avoided even for high κh
when passive oscillations are allowed. Passive pitching modulated the relative foil orientation with respect to the incoming free stream to maintain a lower effective angle-of-attack throughout the stroke and reduced the leading-edge-vortex (LEV) strength. Absence of aperiodic triggers such as flow separation and strong LEVs keep the wake periodic, and chaotic transition is averted. In the presence of fluctuating inflow conditions, passive pitching attenuated the fluid loads experienced by the airfoil thus improving the wing’s gust mitigating potential. These findings highlight the favorable properties of passive dynamics in regularizing aerodynamic loads on flapping wing systems and presents viable solutions for artificial flying platforms.
). Here we considered the idealized case of a pitching–plunging flapping foil and numerically investigated the effects of passive pitching dynamics on the fluid forces and dynamical states, and compared it with a fully actuated wing. We found that in comparison to fully actuated foils, aperiodic transition can be avoided even for high κh
when passive oscillations are allowed. Passive pitching modulated the relative foil orientation with respect to the incoming free stream to maintain a lower effective angle-of-attack throughout the stroke and reduced the leading-edge-vortex (LEV) strength. Absence of aperiodic triggers such as flow separation and strong LEVs keep the wake periodic, and chaotic transition is averted. In the presence of fluctuating inflow conditions, passive pitching attenuated the fluid loads experienced by the airfoil thus improving the wing’s gust mitigating potential. These findings highlight the favorable properties of passive dynamics in regularizing aerodynamic loads on flapping wing systems and presents viable solutions for artificial flying platforms.
Editor(s)
Żur, Krzysztof
Date Issued
2023-04-03
Date Acceptance
2023-03-08
Citation
PNAS Nexus, 2023, 2 (4), pp.1-10
ISSN
2752-6542
Publisher
Oxford University Press
Start Page
1
End Page
10
Journal / Book Title
PNAS Nexus
Volume
2
Issue
4
Copyright Statement
© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
Identifier
http://dx.doi.org/10.1093/pnasnexus/pgad086
Publication Status
Published
Date Publish Online
2023-03-22