Theory of cross-correlation analysis of PIV images
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To improve the performance of particle image velocimetry in measuring instantaneous velocity fields, direct cross-correlation of image fields can be used in place of auto-correlation methods of interrogation of double- or multiple-exposure recordings. With improved speed of photographic recording and increased resolution of video array detectors, cross-correlation methods of interrogation of successive single-exposure frames can be used to measure the separation of pairs of particle images between successive frames. By knowing the extent of image shifting used in a multiple-exposure and by a priori knowledge of the mean flow-field, the cross-correlation of different sized interrogation spots with known separation can be optimized in terms of spatial resolution, detection rate, accuracy and reliability.
For the direct cross-correlation method of single-exposure, double-frame systems which model video array detector interrogation and of double-exposure single-frame systems which generalize earlier direct auto-correlation methods of interrogation of photographic recordings, optimal system parameters are recommended for a range of velocity fields in order to eliminate signal bias and to minimize loss of signal strength. The signal bias resulting from velocity gradients in auto-correlation analysis can be eliminated in cross-correlation interrogation by appropriate choice of the optimal parameters. Resolution, detection rate, accuracy and reliability are compared with direct auto-correlation methods for double- and multiple-pulsed systems.
Key wordsPIV cross-correlation auto-correlation
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- 1.Adrian, R. J., Statistical properties of particle image velocimetry measurements in turbulent flow. Laser Anemometry in Fluid Mechanics, Vol. III. LADOAN Institute Superior Tecnico, Lisbon, Portugal (1988) pp. 115–129.Google Scholar
- 2.Adrian, R. J. and Zoltani, C., Measurement of particulate motion using a high resolution solid-state camera and high speed electro-optic double framing. Abstract ICALEO (1990).Google Scholar
- 3.Arroyo, M. P., Yonte, T., Quintanilla, M. and Savirón, J. M., Particle image velocimetry in Rayleigh-Bénard convection: Photographs with high number of exposures. Optics and Lasers in Engineering 9 (1988) 295–316.Google Scholar
- 4.Cenedese, A. and Paglialunga, A., Digital direct analysis of a multi-exposed photograph in PIV. Experiments in Fluids 8 (1990) 273–280.Google Scholar
- 5.Goss, L. P., Post, M. E., Trump, D. D. and Sarka, B., Two color particle velocimetry. Proc. ICALEO, LIA 68 (1989) pp. 101–111.Google Scholar
- 6.Keane, R. D. and Adrian, R. J., Optimization of particle image velocimeters. Part I: Double-pulsed systems. Measurement Science and Technology 1 (1990) 1202–1215.Google Scholar
- 7.Keane, R. D. and Adrian, R. J., Optimization of particle image velocimeters. Part II: Multiple-pulsed systems. Measurement Science and Technology 2 (1991) 963–974.Google Scholar
- 8.Keane, R. D., Adrian, R. J. and Ford, D. K., Single exposure double frame particle image velocimeters. Proc. ICALEO 72 (1990) 91–110.Google Scholar
- 9.Kimura, I. and Takamori, T., Image processing of flow around a circular cylinder by using correlation techniques. In: Veret, C. (ed.), Flow Visualization IV. Washington, D.C.: Hemisphere Publishing Corp (1986) pp. 221–226.Google Scholar
- 10.Lee, M. M., Hanratty, T. J. and Adrian, R. J., An axial viewing photographic technique to study turbulence characteristics of particles. Int. J. Multiphase Flow 15 (1989) 787–802.Google Scholar
- 11.Lourenco, L. M. and Krothapalli, A., The role of photographic parameters in laser speckle or particle image displacement velocimetry. Experiments in Fluids 5 (1987) 29–32.Google Scholar
- 12.Meynart, R., Simpkins, P. G. and Dudderar, T. D., Speckle measurements of convection in a liquid cooled from above. J. Fluid Mech 182 (1987) 235–254.Google Scholar
- 13.Prasad, A. K., Adrian, R. J., Landreth, C. C. and Offutt, P. W., Effect of resolution on the speed and accuracy of particle image velocimetry interrogation. Experiments in Fluids 13 (1992) 105–116.Google Scholar
- 14.Utami, T., Blackwelder, R. F. and Ueno, T., A cross-correlation technique for velocity field extraction from particulate visualization. Experiments in Fluids 10 (1991) 213–223.Google Scholar
- 15.Willert, C. E. and Gharib, M., Digital particle image velocimetry. Experiments in Fluids 10 (1991) 181–193.Google Scholar
- 16.Yao, C. S. and Adrian, R. J., Orthogonal compression and 1-D analysis technique for measurement of particle displacements in pulsed laser velocimetry. Applied Optics 23 (1984) 1687–1689.Google Scholar