onsdag 27 juli 2011
Mathematical Secret of Flight 5: Bird Wing
The thesis by Heather Falconsong Howard studies techniques for generating photo-realistic and fantasy digital bird and avian creatures in film, TV and games, based on an analysis of the design of real birds wings.
Particular attention is given to little covert feathers covering the space between groups of main fetahers, which also seem to act like little wing flaps delaying separation.
This is indicated in the above picture from the thesis which represents the classical Prandtl scenario of separation based on 2d recirculation to stagnation.
Our new analysis of separation and generation of lift opens to a different understanding of the action of birds wings. In particular we expect to find a connection between the separation pattern of our new analysis with point-stagnation and streamwise vorticity, and the arrangement of feathers of a bird wing including covert feathers and a periodic wavy trailing edge. We will report on our findings in upcoming posts...
The design of birds' wings thus suggest that the smooth surface and sharp straight trailing edge of a standard airplane wing may not be optimal. A further indication in this direction is given by the slotted wing tips of gliding hawks and the slotted jet flaps of Skywalk paragliders, to which we will also return...