Abstract
Two dimensional velocity distributions at an open-channel confluence were obtained by applying the image processing technique. In this study, the so-called correlation technique was used to analyze visualized flow patterns at the water surface. The correlation technique was improved by considering small rotations of the reference frame to be applicable to the vortical flow field. The improved method gave good results especially in the region of separated shear layer at the confluence. Also, the accuracy of this technique was examined in detail.
