Computation of Low Reynolds Number Flexible Flapping Wing Aerodynamics Using Overlapping Grids

The dynamic interaction of a flexible body with the surrounding flow at Low Reynolds numbers is studied in detail computationally using the unsteady incompressible Navier Stokes equations on moving and deforming overlapping grids embodied in the flow solver cgins/OverBlown. Various computations are carried out to explore the fascinating dynamics of thin airfoils and wings. The flow solver is first validated by considering a standard test case of a plunging and deforming NACA 0014 airfoil. It is further observed that the Geometric Conservation Law has a minor impact on computed solutions when grids are generated through a hyperbolic mapping with a smaller marching distance. From the results of the passive flight of a plunging and deforming tear drop plate, it can be inferred that the most flexible plate propels forward with the largest speed. The effect of pressure and shear stress on trajectories is also examined. Three-dimensional computations for a flexible wing have also been carried out and the observed vortex patterns are seen to be consistent with the kinematics of the problem. Two different types of kinematics have been examined and it is observed that asymmetry in the size of leading and trailing edge vortices gives rise to thrust