Free-flight analysis of dragonfly hovering by fluid-structure interaction analysis based on an arbitrary Lagrangian-Eulerian method

摘要

A 'free-flight' simulation of flapping flight based on fluid-structure interaction analysis, which can treat the large deformation of wings quantitatively, is applied to the hovering of the dragonfly. Recently, experimental methods and numerical simulation have made significant progress in solving the unsteady aerodynamics of flapping flight, and succeeded in quantifying it under a tethered situation. However, to analyze the stability of hovering or acrobatic flight modes, free-flight simulation is essential. Especially, the structural dynamics of a light and resultantly deformable wing may seriously affect the controllability of flight. We implement the interaction between a body and wing in the fluid-structure interaction analysis, and solve the free-flight situation, where the wing lifts the body and the body actuates the wing. Although the modeled dragonfly is artificially designed to have only two wings to avoid needing to consider the problem of contact between wings and it might, therefore, have less controllability than the real dragonfly, the free-flight simulation closely matches the real stable flight of the dragonfly, thus demonstrating of the adequacy of the simulation. In addition, the altitude and pitch angle of the body are confirmed to be recovered by slight artificial tilt of the stroke plane.