Leading edge vortex stably attached near the base of a freely flying maple seed Acer pseudo-platanus

Supporting Online Material for "Leading-Edge Vortices Elevate Lift of Autorotating Plant Seeds," D. Lentink, W.B. Dickson, J.L. van Leeuwen and M.H. Dickinson, Science 12 June 2009: Vol. 324. no. 5933, pp. 1438 - 1440 http://dx.doi.org/10.1126/science.117...

Abstract: "As they descend, the autorotating seeds of maples and some other trees generate unexpectedly high lift, but how they attain this elevated performance is unknown. To elucidate the mechanisms responsible, we measured the three-dimensional flow around dynamically scaled models of maple and hornbeam seeds. Our results indicate that these seeds attain high lift by generating a stable leading-edge vortex (LEV) as they descend. The compact LEV, which we verified on real specimens, allows maple seeds to remain in the air more effectively than do a variety of nonautorotating seeds. LEVs also explain the high lift generated by hovering insects, bats, and possibly birds, suggesting that the use of LEVs represents a convergent aerodynamic solution in the evolution of flight performance in both animals and plants."

Explanation "The movie shows a leading edge vortex that is stably attached near the base of a freely flying maple seed (Acer pseudo-platanus L.). The seed is spinning at stationary height in a vertical wind tunnel and the flow is visualized at different spanwise stations using a laser light sheet. The laser light sheet illuminates the motion of smoke particles dispersed in the air around the wing that trace the airflow. The seed has a small horizontal speed and, therefore, the seed flies slowly out of the laser sheet. As a result the local airflow is visualized at successively more outward spanwise stations of the spinning seed."

See http://www.sciencemag.org/cgi/data/32... for further details and explanation of key frames.

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  Science & Technology

[hectorleon]

nice!