Experiments in Fluids

, Volume 53, Issue 5, pp 1487–1500 | Cite as

Accurate measurement of streamwise vortices using dual-plane PIV

  • Rye M. Waldman
  • Kenneth S. Breuer
Research Article


Low Reynolds number aerodynamic experiments with flapping animals (such as bats and small birds) are of particular interest due to their application to micro air vehicles which operate in a similar parameter space. Previous PIV wake measurements described the structures left by bats and birds and provided insight into the time history of their aerodynamic force generation; however, these studies have faced difficulty drawing quantitative conclusions based on said measurements. The highly three-dimensional and unsteady nature of the flows associated with flapping flight are major challenges for accurate measurements. The challenge of animal flight measurements is finding small flow features in a large field of view at high speed with limited laser energy and camera resolution. Cross-stream measurement is further complicated by the predominately out-of-plane flow that requires thick laser sheets and short inter-frame times, which increase noise and measurement uncertainty. Choosing appropriate experimental parameters requires compromise between the spatial and temporal resolution and the dynamic range of the measurement. To explore these challenges, we do a case study on the wake of a fixed wing. The fixed model simplifies the experiment and allows direct measurements of the aerodynamic forces via load cell. We present a detailed analysis of the wake measurements, discuss the criteria for making accurate measurements, and present a solution for making quantitative aerodynamic load measurements behind free-flyers.


Vortex Vorticity Vortex Core Laser Sheet Freestream Velocity 
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.



This work was supported by the AFOSR MURI on Bio-inspired flight, monitored by Drs. Doug Smith and Willard Larkin.


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.School of EngineeringBrown UniversityProvidenceUSA

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