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


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.


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.



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.


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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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