Computations of Insect and Fish Locomotion with Applications to Unconventional Unmanned Vehicles

Abstract

Living creatures such as insects, birds, and fish generate lift and thrust most often by executing large-amplitude wing flapping, possibly with substantial shape deformation from root to tip. The flow for these motions is unsteady, and conventional steady-state aerodynamics is unable to correctly compute the time history of their flapping-force generation. Three-dimensional unsteady computations of flapping about the deforming wing or fin surface are necessary to correctly predict the lift and thrust throughout the flapping cycle. It is only by executing such computations for creatures or vehicles with moving and deforming surfaces that we can gain insights into the time-varying pressure distribution on all surfaces and how that results in flapping-force generation. This can be coupled with visualization of the origination and evolution of body, wing, and wake vorticity. Three-dimensional unsteady flow computations of the flapping flights of the fruit fly, a pectoral-fin swimmer (the bird wrasse), and a variety of unmanned air vehicles were carried out in pursuit of this information. The performance of these flapping wings under gust conditions was also investigated. The effect of fin deformation on the force production was studied. Novel biomimetic vehicles, incorporating information gained from these computations, were designed and built and their performance is described.