Acta Mechanica Sinica

, Volume 21, Issue 5, pp 411–418 | Cite as

The influence of the wake of a flapping wing on the production of aerodynamic forces

  • Jianghao Wu
  • Mao SunEmail author


The effect of the wake of previous strokes on the aerodynamic forces of a flapping model insect wing is studied using the method of computational fluid dynamics. The wake effect is isolated by comparing the forces and flows of the starting stroke (when the wake has not developed) with those of a later stroke (when the wake has developed). The following has been shown. (1) The wake effect may increase or decrease the lift and drag at the beginning of a half-stroke (downstroke or upstroke), depending on the wing kinematics at stroke reversal. The reason for this is that at the beginning of the half-stroke, the wing ``impinges'' on the spanwise vorticity generated by the wing during stroke reversal and the distribution of the vorticity is sensitive to the wing kinematics at stroke reversal. (2) The wake effect decreases the lift and increases the drag in the rest part of the half-stroke. This is because the wing moves in a downwash field induced by previous half-stroke's starting vortex, tip vortices and attached leading edge vortex (these vortices form a downwash producing vortex ring). (3) The wake effect decreases the mean lift by 6%–18% (depending on wing kinematics at stroke reversal) and slightly increases the mean drag. Therefore, it is detrimental to the aerodynamic performance of the flapping wing.


Insect Flapping Unsteady aerodynamics Wing/wake interaction CFD analysis 


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  1. 1.
    Dickinson, M.H.: The effects of wing rotation on unsteady aerodynamic performance at low Reynolds numbers. J. Exp. Biol. 192, 179–206 (1994)Google Scholar
  2. 2.
    Sun, M., Hossein, H.: A study on the mechanism of high-lift generation by an airfoil in unsteady motion at low Reynolds number. Acta Mechanica Sinica 17, 97–114 (2001)Google Scholar
  3. 3.
    Dickinson, M.H., Lehman, F.O., Sane, S.P.: Wing rotation and the aerodynamic basis of insect flight. Science 284, 1954–1960 (1999)Google Scholar
  4. 4.
    Sun, M., Tang, J.: Unsteady aerodynamic force generation by a model fruit fly wing in flapping motion. J. Exp. Biol. 205, 55–70 (2002)Google Scholar
  5. 5.
    Birch, J.M., Dickinson, M.H.: The Influence of wing-wake interactions on the production of aerodynamic forces in flapping flight. J. Exp. Biol. 206, 2257–2272 (2003)Google Scholar
  6. 6.
    Ellington, C.P.: The aerodynamics of hovering insect flight. III. Kinematics. Phil. Trans. R. Soc. Lond. B 305, 41–78 (2003)Google Scholar
  7. 7.
    Fry, S.N., Sayaman, R., Dickinson, M.H.: The aerodynamics of free-flight maneuvers in drosophila. Science 300, 495–498 (2003)Google Scholar
  8. 8.
    Sun, M., Wu, J.H.: Aerodynamic force generation and power requirements in forward flight in a fruit fly with modeled wing motion. J. Exp. Biol. 206, 3065–3083 (2003)Google Scholar
  9. 9.
    Wu, J.H., Sun, M.: Unsteady aerodynamic forces of a flapping wing. J. of Exp. Biol. 207, 1137–1150 (2004)Google Scholar
  10. 10.
    Sun, M., Wu, J.H.: Large aerodynamic force generation by a sweeping wing at low Reynolds numbers. Acta Mechanica Sinica 20, 24–31 (2004)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  1. 1.Ministry-of-Education Key Laboratory of Fluid Mechanics, Institute of Fluid MechanicsBeihang UniversityBeijingChina

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