The flapping foil is a simple model that contains key dynamical elements, such as the creation and organization of vorticity, that are crucial in every system involving flapping wings or fins as a means of producing propulsive forces. The flow structures in the wake can be visualized as we show here by injecting dye filaments upstream of the foil.

References:

R. Godoy-Diana; J. L. Aider & J. E. Wesfreid. Transitions in the wake of a flapping foil. Physical Review E, 77 : 016308 (2008).

R. Godoy-Diana; C. Marais; J. L. Aider & J. E. Wesfreid. A model for the symmetry breaking of the reverse Bénard-von Kármán vortex street produced by a flapping foil. Journal of Fluid Mechanics, 622 : 23-32 (2009).

C. Marais, & R. Godoy-Diana. Propulsion animale par ailes ou nageoires battantes. Reflets de la physique, 24, 9 (2011).

C. Marais; B Thiria; Wesfreid, J. E. & R. Godoy-Diana. Stabilizing effect of flexibility in the wake of a flapping foil. Journal of Fluid Mechanics, 710 : 659-669 (2012).

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