Three dimensional tracking of particles and their local orientations

In this paper, digital stereoscopic imaging and reconstruction techniques have been developed for the tracking and velocity measurement of solid particles using a single camera. The variable shutter speeds of a digital camera are used to control the trajectory length of the tracked particles. A colour coding method has been developed to resolve the ambiguity of particle flow direction and avoid the confusion in manually matching particle pairs. The method could be applied to validate the automated particle matching algorithms. Besides using points (particle centroids) a matching algorithm for a stereo reconstruction pixel to pixel matching algorithm has been applied. The latter is able to resolve not only the particle position but also the shape and orientation of a non-spherical particle. This is of importance since non-spherical particle or bubble geometry is common in a practical system and the non-spherical geometry has a strong effect on the particle or bubble dynamics. The potential of using this system for the quantitative 3D measurement of multiphase flow has been demonstrated with several test cases.