Movie 1 from Physics of unsteady thrust and flow generation by a flexible surface flapping in the absence of a free stream.

This video is for the airfoil with flexible flap. The flow generation mechanism mentioned in sections 3 and 4 of the main paper is clearly demonstrated: appropriate co-ordination between the motions of the foil and the flexible flap generates the narrow coherent jet along the center-line. The fluid is pulled-in by the airfoil and the flexible flap (largely from the lateral sides) and thrown in the downstream direction as a narrow, coherent reverse Bénard–Kármán vortex jet along the centerline. Shedding of two large counter-rotating vortices in each flapping cycle is clearly seen. Note: The rigid airfoil and a small portion of the transparent flap blackened near its free-end cast the moving shadows in the upper half of the window.