The influence of peak-locking errors on turbulence statistics computed from PIV ensembles
The influence of peak-locking errors on turbulence statistics computed from ensembles of PIV data is considered. PIV measurements are made in the streamwise–wall-normal plane of turbulent channel flow. The PIV images are interrogated in three distinct ways, generating ensembles of velocity fields with absolute, moderate, and minimal peak locking. Turbulence statistics computed for all three ensembles of data indicate a general sensitivity to peak locking in the single-point statistics, except for the mean velocity profile. Peak-locking errors propagate into the fluctuations of velocity, rendering single-point statistics inaccurate when severe peak locking is present. Multi-point correlations of both streamwise and wall-normal velocity are also found to be influenced by severe levels of peak locking. The displacement range of the measurement, defined by the PIV time delay, appears to affect the influence of peak-locking errors on turbulence statistics. Smaller displacement ranges, particularly those that produce displacement fluctuations that are less than one pixel in magnitude, yield inaccurate turbulence statistics in the presence of peak locking.
The author would like to thank Dr. Wing Lai of TSI, Inc. for generously loaning the PIV equipment used in this study. This effort was financially supported by The University of New Mexico. The author would also like to thank the referees for their insightful comments and suggestions.
- Christensen KT (2001) Experimental investigation of acceleration and velocity fields in turbulent channel flow. PhD thesis, Department of Theoretical and Applied Mechanics, University of Illinois at Urbana-Champaign, Urbana, Ill.Google Scholar
- Christensen KT, Adrian RJ (2002) Measurement of instantaneous Eulerian acceleration fields by particle-image accelerometry: method and accuracy. Exp Fluids 33(6):759–769Google Scholar
- Christensen KT, Soloff SM, Adrian RJ (2000) PIV sleuth: integrated particle-image velocimetry (PIV) interrogation/validation software. Technical Report 943, Department of Theoretical and Applied Mechanics, University of Illinois at Urbana-Champaign, Urbana, Ill.Google Scholar
- Reuss DL, Adrian RJ, Landreth CC, French DT, Fansler TD (1989) Instantaneous planar measurements of velocity and large-scale vorticity and strain in an engine using particle-image velocimetry. Technical report, Society of Automotive EngineersGoogle Scholar
- Westerweel J (1997) Fundamentals of digital particle image velocimetry. Meas Sci Tech 8:1379–1392Google Scholar