Many 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.
