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Experiments in Fluids

, 46:933 | Cite as

Time-resolved wake structure and kinematics of bat flight

  • Tatjana Y. Hubel
  • Nickolay I. Hristov
  • Sharon M. Swartz
  • Kenneth S. Breuer
Research Article

Abstract

We present synchronized time-resolved measurements of the wing kinematics and wake velocities for a medium sized bat, Cynopterus brachyotis, flying at low-medium speed in a closed-return wind tunnel. Measurements of the motion of the body and wing joints, as well as the resultant wake velocities in the Trefftz plane are recorded at 200 Hz (approximately 28–31 measurements per wing beat). Circulation profiles are found to be quite repeatable although variations in the flight profile are visible in the wake vortex structures. The circulation has almost constant strength over the middle half of the wing beat (defined according the vertical motion of the wrist, beginning with the downstroke). A strong streamwise vortex is observed to be shed from the wingtip, growing in strength during the downstroke, and persisting during much of the upstroke. At relatively low flight speeds (4.3 m/s), a closed vortex structure behind the bat is postulated.

Keywords

Vortex Particle Image Velocimetry Wind Tunnel Vortex Structure Particle Image Velocimetry Measurement 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

We thank A. Song, R. Waldman and D. Riskin for helpful discussions, and A. Sullivan, L. Macayeal and A. Robb for handling and training of animals and their help with data collection. We are very thankful for the support provided by D. Riskin regarding kinematic analysis and data flow issues. We also thank R. Waldman for the construction of the safety light barrier. We thank the Lubee Bat Conservancy, especially A. Walsh, for the long term access to the bats. This work was supported by the Air Force Office of Scientific Research, monitored by Drs. Rhett Jeffries, John Schmisser and Willard Larkin, and the National Science Foundation. All experiments were conducted with the authorization of the Institutional Animal Care and Use Committees of Brown University, the Lubee Bat Conservancy and the Division of Biomedical Research and Regulatory Compliance of the Office of the Surgeon General of the United States Air Force.

References

  1. Abdel-Aziz YI, Karara HM (1971) Direct linear transformation from comparator coordinates into object space coordinates in close-range photogrammetry. In: Proceedings of the symposium on close-range photogrammetry, American Society of Photogrammetry, Falls Church, pp 1–18Google Scholar
  2. Adrian RJ, Christensen KT, Liu ZC (2000) Analysis and interpretation of instantaneous turbulent velocity fields. Exp Fluids 29:275–290CrossRefGoogle Scholar
  3. Betz A (1932) Verhalten von Wirbelsystemen. Zeitschrift fur angewandte Mathematikund Mechanik 12:164–174 (Also published as NACA TM 713)Google Scholar
  4. Devenport WJ, Rife MC, Liapis SI, Follin GJ (1996) The structure and development of a wing-tip vortex. J Fluid Mech 312:67–106CrossRefMathSciNetGoogle Scholar
  5. Ellington CP (1999) The novel aerodynamics of insect flight: applications to micro-air vehicles. J Exp Biol 202:3439–3448Google Scholar
  6. Ellington CP, van den Berg C, Willmott AP, Thomas ALR (1996) Leading-edge vortices in insect flight. Nature 384:626–630CrossRefGoogle Scholar
  7. Gerontakos P, Lee T (2006) Near-field tip vortex behind a swept wing model. Exp Fluids 40:141–155CrossRefGoogle Scholar
  8. Hedenström A, Johansson LC, Wolf M, von Busse R, Winter Y, Spedding GR (2007) Bat flight generates complex aerodynamic tracks. Science 316:894–897CrossRefGoogle Scholar
  9. Hedenström A, Rosén M, Spedding GR (2006) Vortex wakes generated by robins Erithacus rubecula during free flight in a wind tunnel. J Royal Soc Interface 3:263–276CrossRefGoogle Scholar
  10. Iriarte-Diaz J, Riskin DK, Willis DJ, Breuer KS, Swartz SM (2009a) No net thrust on the upstroke: whole-body kinematics of a fruit bat reveal the influence of wing inertia on body accelerations (in review)Google Scholar
  11. Iriarte-Diaz J, Riskin DK, Swartz SM (2009b) Modulation of wingbeat kinematics with flight speed in the fruit bat Cynopterus brachyotis (in prep.)Google Scholar
  12. Lilienthal O (1889) Der Vogelflug als Grundlage der. Fliegekunst Leipzig: GaertuerGoogle Scholar
  13. Muijres FT, Johansson LC, Barfield R, Wolf M, Spedding GR, Hedenstrom A (2008) Leading-edge vortex improves lift in slow-flying bats. Science 319:1250–1253CrossRefGoogle Scholar
  14. Neuweiler G (2000) The biology of bats. Oxford University Press, OxfordGoogle Scholar
  15. Nowak RN (1994) Walker’s bats of the world. Johns Hopkins University Press, BaltimoreGoogle Scholar
  16. Pennycuick CJ (1968) Power requirements for horizontal flight in the pigeon Columba Livia. J Exp Biol 49:527–555Google Scholar
  17. Rayner JMV (1979) A vortex theory of animal flight. Part 2: the forward flight of birds. J Fluid Mech 91:731–763zbMATHCrossRefGoogle Scholar
  18. Riskin DK, Willis DJ, Iriarte-Díaz J, Hedrick TL, Kostandov M, Chen J, Laidlaw DH, Breuer KS, Swartz SM (2008) Quantifying the complexity of bat wing kinematics. J Theor Biol 254:604–615CrossRefGoogle Scholar
  19. Sane SP (2003) The aerodynamics of insect flight. J Exp Biol 206:4191–4208. doi: 10.1242/jeb.00663 CrossRefGoogle Scholar
  20. Spedding GR (1986) The wake of a jackdaw (Corvus Monedula) in slow flight. J Exp Biol 125:287–307Google Scholar
  21. Spedding GR (1987) The wake of a kestrel (Falco Tinnunculus) in flapping flight. J Exp Biol 127:59–78Google Scholar
  22. Spedding GR, Rayner JMV, Pennycuick CJ (1984) Momentum and energy in the wake of a pigeon (Columba Livia) in slow flight. J Exp Biol 111:81–102Google Scholar
  23. Spedding GR, Rosen M, Hedenström A (2003) A family of vortex wakes generated by a thrush nightingale in free flight in a wind tunnel over its entire natural range of flight speeds. J Exp Biol 206:2313–2344. doi: 10.1242/jeb.00423 CrossRefGoogle Scholar
  24. Swartz SM, Groves MS, Kim HD, Walsh WR (1996) Mechanical properties of bat wing membrane skin. J Zool 239:357–378CrossRefGoogle Scholar
  25. Swartz SM, Bishop KL, Ismael-Aguirre M-F (2006) Dynamic complexity of wing form in bats: implications for flight performance. In: Akbar Z, McCracken G, Kunz T (eds) Functional and evolutionary ecology of bats. Oxford University Press, OxfordGoogle Scholar
  26. Tian X, Iriarte-Diaz J, Middleton K, Galvao R, Israeli E, Roemer A, Sullivan A, Song A, Swartz S, Breuer K (2006) Direct measurements of the kinematics and dynamics of bat flight. Bioinspir Biomim 1:10–18CrossRefGoogle Scholar
  27. Tobalske BW, Hedrick TL, Dial KP, Biewener AA (2003a) Comparative power curves in bird flight. Nature 421:363–366CrossRefGoogle Scholar
  28. Tobalske BW, Hedrick TL, Biewener AA (2003b) Wing kinematics of avian flight across speeds. J Avian Biol 34:177–184CrossRefGoogle Scholar
  29. Willis DJ, Israeli ER, Persson P-O, Drela M, Peraire J, Swartz SM, Breuer KS (2007) A computational framework for fluid structure interaction in biologically inspired flapping flight. In: AIAA applied aerodynamics meeting, vol 1, pp 38–59, American Institute of Aeronautics and Astronautics Inc, Miami, United States, Reston, VA 20191–4344, United StatesGoogle Scholar

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Tatjana Y. Hubel
    • 1
  • Nickolay I. Hristov
    • 1
  • Sharon M. Swartz
    • 1
  • Kenneth S. Breuer
    • 1
  1. 1.Brown UniversityProvidenceUSA

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