Application of wavelet technique to false vector correction and data compression in PIV

Abstract

A wavelet-based vector compression technique was proposed as a new technique of PIV post-processing for efficiently eliminating erroneous vectors and reducing physical storage. To determine the effect of the choice of wavelet bases, the velocity vector field obtained from standard PIV images was compressed using some known wavelet functions, such as Daubechies, Coifman and Baylkin families. It was found that the lower-order wavelet bases provide good compression performance because they have good physical localization, which in turn, increases energy compaction. When being applied to the PIV result of a jet, the correction of erroneous vectors can be realized by increasing the compression ratio to 16.