Insects rely on their olfactory system to forage, prey, and mate. They can sense odorant plumes emitted from sources of their interests with their bilateral odorant antennae, and track down odor sources using their highly efficient flapping-wing mechanism. The odor-tracking process typically consists of two distinct behaviors: surging upwind and zigzagging crosswind. Despite the extensive numerical and experimental studies on the flying trajectories and wing flapping kinematics during odor tracking flight, we have limited understanding of how the flying trajectories and flapping wings modulate odor plume structures. In this study, a fully coupled three-way numerical solver is developed, which solves the 3D Navier-Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant convection-diffusion equation. This numerical solver is applied to investigate the unsteady flow field and the odorant transport phenomena of a fruit fly model in both surging upwind and zigzagging crosswind cases. The unsteady flow generated by flapping wings perturbs the odor plume structure and significantly impacts the odor intensity at the olfactory receptors (i.e., antennae). During zigzagging crosswind flight, the differences in odor perception time and peak odor intensity at the receptors potentially help create stereo odorant mapping to track odor source. Our simulation results will provide new insights into the mechanism of how fruit flies perceive odor landscape and inspire the future design of odor-guided micro aerial vehicles (MAVs) for surveillance and detection missions.
- NSF-PAR ID:
- 10308831
- Date Published:
- Journal Name:
- AIAA AVIATION 2021 FORUM
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Odor-guided navigation is an indispensable aspect of flying insects' behavior, facilitating crucial activities such as foraging and mating. The interaction between aerodynamics and olfaction plays a pivotal role in the odor-guided flight behaviors of insects, yet the interplay of these two functions remains incompletely understood. In this study, we developed a fully coupled three-way numerical solver, which solves the three-dimensional Navier–Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant advection–diffusion equation. This numerical solver is applied to investigate the unsteady flow field and the odorant transport phenomena of a fruit fly model in odor-guided upwind surge flight over a broad spectrum of reduced frequencies (0.325–1.3) and Reynolds numbers (90–360). Our results uncover a complex dependency between flight velocity and odor plume perception, modulated by the reduced frequency of flapping flight. At low reduced frequencies, the flapping wings disrupt the odor plume, creating a saddle point of air flow near the insect's thorax. Conversely, at high reduced frequencies, the wing-induced flow generates a stagnation point, in addition to the saddle point, that alters the aerodynamic environment around the insect's antennae, thereby reducing odor sensitivity but increasing the sampling range. Moreover, an increase in Reynolds number was found to significantly enhance odor sensitivity due to the synergistic effects of greater odor diffusivity and stronger wing-induced flow. These insights hold considerable implications for the design of bio-inspired, odor-guided micro air vehicles in applications like surveillance and detection.
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Abstract Insects rely on their olfactory system to forage, prey, and mate. They can sense odorant plumes emitted from sources of their interests with their bilateral odorant antennae, and track down odor sources using their highly efficient flapping-wing mechanism. The odor-tracking process typically consists of two distinct behaviors: surging upwind at higher velocity and zigzagging crosswind at lower velocity. Despite extensive numerical and experimental studies on odor guided flight in insects, we have limited understandings on the effects of flight velocity on odor plume structure and its associated odor perception. In this study, a fully coupled three-way numerical solver is developed, which solves the 3D Navier-Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant convection-diffusion equation. This numerical solver is applied to resolve the unsteady flow field and the odor plume transport for a fruit fly model at different flight velocities in terms of reduced frequency. Our results show that the odor plume structure and intensity are strong related to reduced frequency. At smaller reduced frequency (larger forward velocity), odor plume is pushed up during downstroke and draw back during upstroke. At larger reduced frequency (smaller forward velocity), the flapping wings induce a shield-like air flow around the antennae which may greatly increase the odor sampling range. Our finding may explain why flight velocity is important in odor guided flight.
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.2514/6.2021-2817
