Abstract
Post-processing of PIV (particle image velocimetry) data typically contains three following stages: validation of the raw data, replacement of spurious and missing vectors, and some smoothing. A robust post-processing technique that carries out these steps simultaneously is proposed. The new all-in-one method (DCT–PLS), based on a penalized least squares approach (PLS), combines the use of the discrete cosine transform (DCT) and the generalized cross-validation, thus allowing fast unsupervised smoothing of PIV data. The DCT–PLS was compared with conventional methods, including the normalized median test, for post-processing of simulated and experimental raw PIV velocity fields. The DCT–PLS was shown to be more efficient than the usual methods, especially in the presence of clustered outliers. It was also demonstrated that the DCT–PLS can easily deal with a large amount of missing data. Because the proposed algorithm works in any dimension, the DCT–PLS is also suitable for post-processing of volumetric three-component PIV data.
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Appendix
Appendix
The supplemental material contains one Matlab program (pppiv, Post-Processing of PIV data) that includes all the properties described in this paper. It carries out automatic and robust post-processing of 2-D PIV data. Enter “help pppiv” in the Matlab command window to obtain a detailed description, the syntax for pppiv and one example. Updated versions of pppiv are also downloadable from the author’s personal website (Garcia 2010a).
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Garcia, D. A fast all-in-one method for automated post-processing of PIV data. Exp Fluids 50, 1247–1259 (2011). https://doi.org/10.1007/s00348-010-0985-y
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DOI: https://doi.org/10.1007/s00348-010-0985-y