A correlation-based continuous window-shift technique to reduce the peak-locking effect in digital PIV image evaluation |
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Authors: | L Gui S T Wereley |
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Institution: | (1) Mechanical Engineering, Purdue University West Lafayette, IN 47907-1288, USA e-mail: lcgui@yahoo.com, US |
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Abstract: | In this paper the peak-locking phenomenon is investigated in the evaluation of digital PIV recordings by using a correlation-based
interrogation algorithm with a discrete window shift and a correlation-based tracking algorithm. Statistical analyses indicate
that nonuniformly distributed bias errors are the main cause of the peak-locking effect, and the amplitude variation of the
random error is also an important source of the peak locking. Simulations and experimental examples demonstrate that very
strong peak-locking effects exist for the correlation-based interrogation algorithm with discrete window shift in the cases
of large particle images, small interrogation windows, and very small particle images. Very strong peak-locking effects are
also observed for the correlation-based tracking algorithm when the particle images are overexposed, binarized, or very small.
These strong peak-locking effects can be avoided without loss of evaluation accuracy by using a continuous window-shift technique
in combination with the correlation-based interrogation algorithm.
Received: 2 July 2001 / Accepted: 28 November 2001 |
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