Computational Study of the Free Flight of a Flapping Wing at Low Reynolds Numbers

Abstract

The application of computational aerodynamics for the design of micro aerial vehicles is increasingly becoming popular. One such area that has achieved good progress is in the development of tools for simulating moving bodies in low Reynolds number flow conditions with specified body kinematics. Using numerical and experimental data, scientists have been able to understand the basic mechanism of force generation in flapping airfoils and wings. However there is a paucity of experimental or computational studies for the free flight of a flapping wing in the literature. This work addresses the problem of free flight of a flapping wing aimed at understanding the combined effects of various flapping modes on thrust and lift generation. Solutions to the unsteady incompressible Navier Stokes equations coupled with rigid body dynamics on moving overlapping meshes are obtained at low Reynolds number flight. Trajectories are computed for a flapping wing with different modes of oscillation. It is observed that, independent periodic oscillation of wings produces less thrust compared to the combined oscillation modes. The effect of initial conditions on forward motion is also analyzed. Vorticity plots and particle traces show interesting flow patterns in the vicinity of the wing.