Improved PIV analysis using an interpolation technique (analysis on improvement effects of the fourier interpolation using quasi particle-images)

We attempted to improve accuracy of particle image velocimetry (PIV) analysis using cross correlation function by introducing method to interpolate the brightness distribution of the measurement images. The motivation of introduction of the interpolation is that uncertainty included in the measurement result may be decreased by introduction of a certain interpolation method. The Fourier interpolation was introduced as the interpolation method focused on that the brightness distribution of a particle can be well approximated by the Gaussian profile, and Fourier transform of the Gaussian profile is equal to the exponential function. Specifically, the sine-function interpolation, which is a kind of the Fourier interpolation, was used, because the brightness distribution is not periodic. The effects of interpolation were investigated by a numerical simulation using quasi particle-images. Parameters in the simulation are moving distance, the particle diameter and the camera noise. This analysis showed that introduction of the interpolation can decrease uncertainty included in the PIV result.