Unsteady aerodynamic model of flapping wings

Propulsive forces can be generated with flapping or heaving wings traveling through a fluid, as demonstrated in animal flight. To examine the flowfield around variable geometry bodies, with specific application to the unsteady flow associated with flapping wings, an unsteady, three-dimensional, incompressible, potential flow model was developed. The problem is formulated in an inertial reference frame such that the body moves through an otherwise quiescent fluid. Results were compared with the limited experimental results available and analytical methods. In one case the model was applied to a flapping wing in a wind tunnel at high advance ratios (J = 4.31) where the computed average lift and thrust were within the error bounds of the experimental data. The model was also applied to high-frequency flapping flight (J = 0.76) of a pigeon flying in a wind tunnel, where the predicted lift matched the weight of the bird.