Collaborative Research: Flying snakes: fluid mechanics of deforming articulated bodies

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There are numerous forms of flight ranging from the natural flapping of insect wings to engineered multi-rotor helicopters. Among the diversity of systems for producing flight forces, the flying snake embodies a highly unexpected and non-intuitive solution for aerial locomotion. With a cylindrical body, the snake has no extendable surfaces to create or control flight forces. Despite these limitations, the Asian arboreal species known as ‘flying’ snakes possess a surprisingly sophisticated ability to glide. These snakes jump from trees, flatten their body, and undulate in the air in a complex three-dimensional pattern to produce aerial locomotion. Most surprisingly, the snakes can actively maneuver in the air, capable of turning in mid-air under their own volition. Understanding how flying snakes achieve such feats is the first step toward duplicating this behavior in engineered devices, which could significantly advance design of robots in complex environments, with important applications to surveillance, search-and-rescue, and disaster monitoring. The aerial interaction physics of flying snakes - the strong coupling between the translational and rotational degrees of freedom of the snake as an articulated body - is largely unknown. This project will test the hypothesis that translational-rotational coupling is achieved through feedback between self-deformations (driven by undulation) and unsteady fluid mechanics. The research will use a combination of animal observations, experimental fluid mechanics, and computational fluid dynamics to reveal the fluid mechanics of deforming articulated bodies, of which the flying snake (genus Chrysopelea) is the prime example. The application of adaptive mesh refinement-based immersed boundary method to study fluid flows produced by gliding snakes will enable more efficient investigations on other complex fluids problems with dynamically moving objects across a wide range of Reynolds numbers. The proposed experimental and computational framework can potentially re-define the form and function of locomotion in fluid media for aerial and underwater robotic systems with enhanced mobility. The project involves a broad participation plan that will benefit a diverse range of groups. The principal investigators will engage under-represented students through programmatic connections to regional HBCUs, for summer undergraduate research as well as recruiting of graduate research assistants, at the three collaborating universities. Flying snakes excite the imagination of both students and the public, and the results of the experiments and computations will be disseminated both professionally and publicly, to media outlets and also directly to the public through social media.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.