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Flapping wings of insects serve for both generating aerodynamic forces and enhancing olfactory sensitivities when navigating on the odor-rich planet. Despite the extensive investigations of the aerodynamic function of flapping wings, we have limited understanding of how the flapping wings potentially affect the physiological sensitivities during flight. In this paper, direct numerical simulations were used to investigate a fruit fly model in an upwind surging motion. The wing pitch kinematics were prescribed using a hyperbolic function, which can change the wing pitch profile from a sinusoidal function to a step function by adjusting the “C” factor in the hyperbolic function. Both aerodynamic performance and olfactory detections were quantified at various wing pitch kinematics patterns. The effects of flapping wings on the odor transport were visualized using the Lagrangian approach by uniformly releasing passive odor tracers in upstream. The study revealed that the insect had the potential to achieve higher aerodynamic performance by tailoring wing pitch kinematics, but it could reduce the odor mass flux around the antenna. It was suspected that the natural flyers might sacrifice certain aerodynamic potential to enhance their olfactory sensitivity for surviving purposes. In addition, a trap-and-flick mechanism is proposed here during the supination phase in order to enhance the olfactory sensitivity. Similar to the clip-and-fling mechanism for enhancing the force generation during the pronation phase, the newly proposed trap-and-flick mechanism is also due to the wing-wing interaction in flapping flight. These findings could provide important implications for engineering applications of odor-guided flapping flight.
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This content will become publicly available on August 29, 2026
Universal vortex formation time of flapping flight
Biological flyers periodically flap their appendages to generate aerodynamic forces. Extensive studies have made significant progress in explaining the physics behind their propulsion in cruising by developing scaling laws of their flight kinematics. Notably Strouhal number (St; ratio of flapping frequency times stroke amplitude to cruising speed) has been found to fall in a narrow range for animal cruising flights. However, St exhibits strong correlation to flight conditions; as such, its universality has been confined to preferred flight conditions. Since the leading-edge vortices (LEV) on flapping appendages generate the majority of propulsive forces, here we take the perspective of LEV circulation maximization, which generalizes the dimensionless vortex formation time to flapping flight. The generalized vortex formation time scales the duration of vorticity injection with the rate of total vorticity growth inside the LEV and the maximum vorticity allowed inside it. By comparing the new scaling with St of previously reported animal cruising flights of 28 species, we show that the generalized vortex formation time is consistent across different animals and cruising locomotion, independent of flight conditions. This finding advances the fundamental principles underlying the complex wing kinematics of biological flyers and highlights a unifying framework for understanding biolocomotion.
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- PAR ID:
- 10650180
- Publisher / Repository:
- Proceedings of the National Academy of Sciences of the United States of America
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 122
- Issue:
- 35
- ISSN:
- 0027-8424
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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