A Computational Study of the Force Generation Mechanisms in Flapping-Wing Hovering Flight

Abstract

An incompressible Navier-Stokes computational fluid dynamics (CFD) solver is developed for simulating flapping wings at Reynolds numbers (<italic>Re</italic>) of approximately 10<super>2</super> - 10<super>3</super> in which the governing equations are solved in an immersed boundary framework on fixed Cartesian meshes. The dissertation work is divided into two portions: (1) Implementation of the immersed boundary method for incompressible low-Re flowfields. The applicability and robustness of various solution schemes are studied, with specific applicability to low <italic>Re</italic> biological flows (staggered variable formulations versus collocated implementations, upwind schemes as applied to incompressible flows, ray-tracing and geometric optimization of immersed boundary determination, Large Eddy Simulation (LES) model implementations). (2) The extension and application of the flow solver (IBINS) to model flapping-wing kinematics, and the analysis of the influence of kinematics and flow parameters on the force production for idealized flapping strokes. A representative <italic>Drosophila</italic> wing is simulated undergoing an idealized periodic flapping stroke. A detailed characterization of the vortical structures that develop in the near and far wake, along with their correlation with the force and power time histories, is given for simulations of various stroke kinematics at <italic>Re</italic> = 147 and <italic>Re</italic> = 1400.