Improvement of measurement accuracy in micro PIV by image overlapping |
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Authors: | Chuong Vinh Nguyen Andreas Fouras Josie Carberry |
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Institution: | (1) Fluid Laboratory for Aeronautical and Industrial Research (FLAIR), Monash University, Melbourne, VIC, 3800, Australia;(2) Division of Biological Engineering, Monash University, Melbourne, VIC, 3800, Australia |
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Abstract: | Micro PIV uses volume illumination; therefore, the velocity measured at the focal plane is a weighted average of the velocities
within the measurement volume. The contribution of out-of-focus particles to the PIV correlation can generate significant
measurement errors particularly in near wall regions. We present a new application of image overlapping, which is shown to
be very effective in improving the accuracy of time-averaged velocity measurements by effectively reducing the measurement
depth. The performance of image overlapping and correlation averaging were studied using synthetic and experimental images
of micro channel flow, both with and without image pre-processing. The results show that for flows without particle clumping,
image overlapping provides the best measurement accuracy without any need for image pre-processing. For flows with particle
clumping, image overlapping combined with band-pass filtering provides the best measurement accuracy. When overlapped images
are saturated with particles due to a large number of image pairs, image overlapping measurement still does not show any visible
pixel-locking effect. Image overlapping was found to have comparable or slightly reduced pixel-locking effects compared to
correlation averaging. In addition, image overlapping utilizes significantly fewer computational resources than the other
techniques. |
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Keywords: | |
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