Authors: A Susset J M Most D Honoré
Publish Date: 2005/10/05
Volume: 40, Issue: 1, Pages: 70-79
Abstract
Three different particle image processing algorithms have been developed for the improvement of PIV velocity measurements characterized by large velocity gradients The objectives of this study are to point out the limitations of the standard processing methods and to propose a complete algorithm to enhance the measurement accuracy The heart of the PIV image processing is a direct crosscorrelation calculation in order to obtain complete flexibility in the choice of the size and the shape of the interrogation window IW An iterative procedure is then applied for the reduction of the size of IW at each measurement location This procedure allows taking into account the local particle concentration in the image The results of this first iterative processing applied to synthetic images show both a significant improvement of measurement accuracy and an increase of the spatial resolution Finally a superresolution algorithm is developed to further increase the spatial resolution of the measurement by determining the displacement of each particle The computer time for a complete image processing is optimized by the introduction of original data storage in Binary Space Partitions trees It is shown that measurement errors for large velocity gradient flows are similar to those obtained in simpler cases with uniform translation displacements This last result validates the ability of the developed superresolution algorithm for the aerodynamic characterization of large velocity gradient flows
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