Abstract
A novel digital particle image velocimetry (DPIV) correlation method is presented, the Gaussian transformed phase correlation (GTPC) estimator, using nonlinear filtering techniques coupled with the phase-transform (PHAT) generalized cross-correlation filter. The use of spatial windowing is shown to be ideally suited for the use of phase correlation estimators, due to their invariance to the loss of correlation effects. Error analysis demonstrates the increased valid vector detection and measurement accuracy of the windowed GTPC over the traditional Fourier based estimator in a series of uniform displacement Monte Carlo simulations. Analysis of the GTPC performance in the PIV standard image sets shows error reductions on the order of 15–45% over the range of simulations. Experimental DPIV images from a turbulent rib roughened channel flow are used to validate the use of the GTPC, which shows a strong reduction in peak locking effects, background noise errors, and erroneous vectors. Together, these results demonstrate the coupled benefits provided by the use of advanced filtering techniques applied to the phase correlation estimator. With the correct implementation of these filters, the GTPC is able to provide substantial improvements to the robustness of DPIV estimation.

















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Abbreviations
- C(i,j):
-
loss of correlation function
- C ij :
-
cross-power spectrum magnitude
- d i :
-
image displacement
- DFT:
-
discrete Fourier transform
- e x :
-
displacement estimation uncertainty
- e Ψ :
-
spatial correlation uncertainty
- F i :
-
in-plane loss of correlation factor
- F o :
-
out-of-plane loss of correlation factor
- G(k):
-
Gaussian temporal filter
- GCC:
-
generalized cross-correlation
- GTPC:
-
Gaussian transformed phase correlation
- GTPCC :
-
bias corrected GTPC
- I i(x):
-
image window intensity distribution
- I i(k):
-
Fourier transformed image window
- I 0i :
-
zeropadded image window
- IDFT:
-
inverse discrete Fourier transform
- M,N :
-
window size
- N i :
-
image window source density
- PHAT:
-
phase transform filtered correlation
- SCC:
-
standard cross-correlation
- SCOT:
-
smoothed coherence transform filter
- W(k):
-
spectral filter
- W(x):
-
spatial window
- δ :
-
discrete delta function
- Ψ:
-
spatial correlation function
References
Adrian RJ (2005) Twenty years of particle image velocimetry. Exp Fluids 39:159–169
Cardwell N (2007) Personal communication. Virginia Polytechnic Institute and State University
Fore L, Tung A (2005) Nonlinear temporal filtering of time-resolved digital particle image velocimetry data. Exp Fluids 39:22–31
Gui L, Longo J, Stern F (2001) Biases of PIV measurement of turbulent flow and the masked correlation-based interrogation algorithm. Exp Fluids 30:27–35
Gui L, Longo J, Fei R (2000) A digital mask technique for reducing the bias error of the correlation-based PIV interrogation algorithm. Exp Fluids 29:30–35
Hart D (2000) PIV error correction. Exp Fluids 29:13–22
Huang HT, Fiedler HE, Wang JJ (1993) Limitation and improvement of PIV, part 2 particle image distortion, a novel technique. Exp Fluids 15:263–273
Huang HT, Dabiri D, Gharib M (1997) On errors of digital particle image velocimetry. Meas Sci Technol 8:1427–1440
Keane RD, Adrian RJ (1992) Theory of cross-correlation analysis of PIV images. App Sci Res 49:191–215
Keane RD, Adrian RJ, Zhang Y (1995) Super-resolution particle imaging velocimetry. Meas Sci Technol 6:754–768
Knapp CH, Carter GC (1976) The generalized correlation method for estimation of time delay. IEEE Trans Acous Speech Sig Proc 24:320–327
Nikias CL, Petropoulou AP (1993) Higher order spectral analysis: a nonlinear signal processing framework. Prentice Hall, New Jersey, pp 313–322
Nogueira J, Lecuona A, Rodriguez PA (1999) Local field correction PIV: on the increase of accuracy of digital PIV systems. Exp Fluids 27:107–116
Nuttall AH (1981) Some windows with very good sidelobe behavior. IEEE Trans Acous Speech Sig Proc ASSP-29:84–91
Okamoto K, Nishio S, Saga T, Kobayashi T (2000) Standard images for particle-image velocimetry. Meas Sci Technol 11:685–691
Raffel M, Willert C, Kompenhans J (1998) Particle image velocimetry: a practicle guide, 3rd edn. Springer, New York, pp 117–146
Scarano F (2002) Iterative image deformation methods in PIV. Meas Sci Technol 13:R1–R19
Shavit U, Lowe RJ, Steinbuck JV (2007) Intensity capping: a simple method to improve cross-correlation PIV results. Exp Fluids 42:225–240
Wereley ST, Meinhart CD (2001) Second-order accurate particle image velocimetry. Exp Fluids 31:258–268
Wernet MP (2005) Symmetric phase only filtering: a new paradigm for DPIV data processing. Meas Sci Technol 16:601–618
Westerweel J (2000) Theoretical analysis of the measurement precision in particle image velocimetry. Exp Fluids 29:S3–S12
Westerweel J, Dabiri D, Gharib M (1997) The effect of a discrete window offset on the accuracy of cross correlation analysis of digital PIV recordings. Exp Fluids 23:20–28
Willert CE, Gharib M (1991) Digital particle image velocimetry. Exp Fluids 10:181–193
Acknowledgments
The authors would like to thank M. Plesniak and W. Schultz for their support of this project. This material is based upon work supported by the National Science Foundation under Grant No. 0521102.
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Eckstein, A.C., Charonko, J. & Vlachos, P. Phase correlation processing for DPIV measurements. Exp Fluids 45, 485–500 (2008). https://doi.org/10.1007/s00348-008-0492-6
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DOI: https://doi.org/10.1007/s00348-008-0492-6