Comparison of Edge Vortices from Normal and Elliptic Flapping Flat Plates

Computational analysis of elliptic and normal flat plate geometries, sized to wings of small fliers and in a two-dimensional plunging-pitching-flapping motion resulting in hover, is conducted to investigate circulation growth at the leading-edge vortex (LEV) and trailing-edge vortex (TEV). The models are sized to the same aspect ratio, and a Reynolds number of 225 is chosen as it is similar to that observed in small fliers in hover. Results show similar LEV growth and lift production trends for both cases but with differing energy flux mechanisms. A vorticity transport analysis is done to quantify these energy fluxes. The LEV growth and shearing is closely related to the TEV growth and shearing, and the plunging-pitching profile, while the geometry plays a role in the magnitude of vortex creation and intensity of spanwise fluxes only.