Collaborative Research: Flying Snakes: Fluid Mechanics of Deforming Articulated Bodies

有许多形式的飞行，从昆虫翅膀的自然拍打到工程多旋翼直升机。在产生飞行力的各种系统中，飞行蛇体现了一种高度意想不到和非直觉的空中运动解决方案。由于蛇的身体是圆柱形的，所以它没有可伸展的表面来产生或控制飞行力。尽管有这些限制，亚洲的树栖物种“飞”蛇拥有令人惊讶的复杂滑翔能力。这些蛇从树上跳下来，把身体压平，在空中以复杂的三维图案起伏，以产生空中运动。最令人惊讶的是，蛇可以在空中主动机动，能够根据自己的意志在半空中转弯。了解飞蛇是如何实现这些壮举的，是在工程设备中复制这种行为的第一步，这将大大推进复杂环境下机器人的设计，在监视、搜索和救援以及灾难监测方面具有重要应用。飞行蛇的空中相互作用物理-蛇作为一个铰接体的平移和旋转自由度之间的强耦合-在很大程度上是未知的。该项目将测试通过自变形（由波动驱动）和非定常流体力学之间的反馈实现平移-旋转耦合的假设。该研究将结合动物观察、实验流体力学和计算流体动力学来揭示变形铰接体的流体力学，其中飞蛇（Chrysopelea属）是主要的例子。应用基于自适应网格细化的浸入边界方法来研究滑动蛇产生的流体流动，将能够更有效地研究在大雷诺数范围内动态移动物体的其他复杂流体问题。所提出的实验和计算框架可以潜在地重新定义具有增强机动性的空中和水下机器人系统在流体介质中的运动形式和功能。该项目涉及广泛的参与计划，将使各种群体受益。主要研究人员将通过与地区hbcu的项目联系，吸引代表性不足的学生，在三所合作大学进行夏季本科生研究，并招募研究生研究助理。飞行蛇激发了学生和公众的想象力，实验和计算的结果将以专业和公开的方式传播给媒体，也将通过社交媒体直接传播给公众。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.