Abstract
Image analysis methods have become a powerful tool for measuring turbulent flows in recent years. However, the accuracy of the methods in measuring turbulence quantities, e.g. turbulent intensities or Reynolds stress distributions, has not been examined in detail so far. In this research turbulence of a uniform open-channel flow was measured by using a PIV (Particle Image Velocimetry) technique and some PTV (Particle Tracking Velocimetry) techniques. In the case of PTV, the binary cross-correlation method and the recently proposedvector-grsdient-tensor method were compared by combining them with the particle masking technique or the conventional technique using a threshold value as the methods for image binarization. Images captured by a high-speed video camera with 200 fps were used and the mean and the turbulent properties were compared. It was made clear that the PTV techniques are superior to the PIV especially where velocity gradients are large and there are no significant differences between the PTV techniques.
