CAREER: Flapping in the wind - passive mechanisms in insect wings for flight stabilization

许多昆虫，如苍蝇、蜻蜓和蝴蝶，它们惊人的机动技能给我们留下了深刻的印象。它们在微风中轻快地奔跑，拥有这样一种运动的自由，这长期以来一直启发着我们的想象。对昆虫飞行过程中流体力学的研究不仅可以帮助我们揭开自然界迷人现象背后的科学谜团，而且还将改变自主微型飞行器(MAV)的设计。最近的许多努力都致力于了解昆虫翅膀产生升力和推力的机制，并取得了令人振奋的进展。然而，昆虫身体的自由度通常被排除在外，这样人们就可以只专注于拍打翅膀的空气动力学。因此，与自由飞行和机翼诱导流动之间的相互作用有关的一些重要物理现象在很大程度上被忽视了。一个这样的例子是自然界中飞行员利用独特的内置机制在存在干扰的情况下稳定飞行并实现灵活性。智力优势当与身体运动相结合时，昆虫翅膀的拍打运动提供了抵抗平移和旋转干扰对稳定飞行的反阻力和扭矩。此外，PI假设机翼的灵活性还提供了一种通过衰减扑翼上的非定常载荷来抑制干扰的机制。这种被动飞行稳定功能与传统飞机设计截然不同，只需改变机翼运动学就可以很容易地脱离，以便于主动机动。PI将应用精确的数值模拟来研究这些稳定机制所涉及的非定常流动行为，并使用现有的理论方法作为描述减振效果的补充工具。数值方法是基于PI实验室开发的高效浸没边界求解器。该方法能够处理复杂/运动的边界，捕捉流动中详细的涡旋结构，并处理三维流动-结构相互作用。通过这一研究计划，将发现并表征扑翼飞行的新的稳定机制。这项研究将为理解昆虫的多尺度物理和主动飞行控制开辟新的前沿。PI预计，这项研究的结果将对开发有效和高效的仿生MAV控制策略产生直接影响。更广泛的影响更广泛的影响来自高度敏捷的MAV在国防、国土安全和环境安全方面的广泛应用。此外，本研究中发展的计算方法可以扩展到研究自然界中更广泛的自由体运动问题以及与生物和生物医学系统中的流-结构相互作用相关的流物理，例如游动的鱼、心血管系统和喉部。研究项目将涉及研究生、本科生和代表性不足的群体。研究材料将被整合到范德比尔特国际学校教授的课程中，并将采用创新的教学策略进行教学，包括互动课堂活动、合作学习和多种评估方法。通过将高中生和他们的老师纳入研究计划，将接触到K-12学生。将设计动手研讨会和基于网络的互动工具，以帮助K-12学生学习科学。

0954381LuoMany insects such as flies, dragonflies, and butterflies impress us greatly with their amazing maneuvering skills. Dashing briskly in breezes, they possess such a freedom of locomotion which has long inspired us to imagine. The study of fluid dynamics involved in insect flight can not only help us unravel the scientific enigma behind the fascinating phenomena in nature, but also will transform design of autonomous micro air vehicles (MAVs). Many recent efforts have been devoted to understand the mechanisms of lift and thrust generation associated with insect wings and have achieved exciting progress. However, the degree of freedom of the insect body was typically excluded so that one could focus solely on the aerodynamics of the flapping wing. Therefore, some of the important physical phenomena associated with the interaction between the free flight and the wing-induced flow have been largely overlooked. One such example is the unique built-in mechanism that the flyers in nature utilize to stabilize their flight in the presence of disturbances and to achieve agility. Intellectual merits When combined with the body motion, the flapping movement of insect wings provides a counter drag and torque resisting the translational and rotational disturbances to the steady flight. In addition, the PI hypothesizes that the wing flexibility also provides a mechanism for disturbance rejection by attenuating the unsteady loads on the flapping flyers. Such passive flight stabilization features are drastically different from those in the conventional airplane design, and they can be easily disengaged by simply changing the wing kinematics to facilitate an active maneuver. The PI will apply accurate numerical simulations to study the unsteady flow behavior involved in these stabilizing mechanisms and also use an existing theoretical approach as a complementary tool to characterize the damping effect. The numerical approach is based on the efficient immersed-boundary solver developed at the PI's lab. The approach is able to handle complex/moving boundaries, capture detailed vortex structures in the flow, and address the three- dimensional flow-structure interaction. Novel stabilizing mechanisms for the flapping flight will be discovered and characterized through this research program. This research will open a new front for understanding the multiscale physics and active flight control of insects. The PI envisions that the results from this research will have a direct impact on the development of effective and efficient control strategies for biomimetic MAVs. Broader impacts The broader impacts come from extensive applications of the highly agile MAVs in the national defense, homeland security, and environmental safety. In addition, the com- putational approach developed in this research can be extended to study the flow physics associated with broader free-body locomotion problems in nature and that associated with flow-structure interaction in biological and biomedical systems, e.g., swimming fish, cardiovascular systems, and larynges. The research project will involve graduate students, undergraduate students, and under- represented groups. The research materials will be integrated into the courses that the PI teaches at Vanderbilt and will be taught with the innovative teaching strategies including interactive class- room activities, cooperative learning, and multiple assessment methods. K-12 students will be reached through incorporating high school students and their teachers in the research program. Hands-on workshops and web-based interactive tools will be designed to help K-12 students learn the science.