Abstract
This paper compares the accuracy of the novel PIV technique based on the optical flow concept and the conventional PIV with the Gaussian sub-pixel fitting. In the new technique, we take into account of image gradient terms with three consecutive frames in the optical flow treatment in order to improve the accuracy for complex flows. This paper includes: i) the fundamental concept and formula of the new method, ii) experiments with standard PIV images, video sequences of the meandering channel flow in a Japanese old garden and flow images of the Uji river, and iii) the discussion on the measurement accuracy. The result shows that the presented method is superior to the conventional PIV especially in the measurement of instantaneous flow field with rotational motion.
