Three-Dimensional Velocity and Vorticity Measuring and Image Analysis Techniques

This text presents infromation on velocity measurements that are necessary in many fields of fluid mechanics and related disciplines. It includes recent developments in the traditional method of hot-wire anemometry and the state of the art in commercially availbale systems. Novel approaches to this topic, based on videogrammetric principles, are treated in Chapters Three and Four. Chapter Three treats the application of videogrammetry in particle tracking velocimetry. The basic principles and their implementation are described in some detail. Performance tests show that the accuracy of the method is comparable to that of LDA. It is, however, a fully three-dimensional measuring technique, capable of determining long particle trajectories which are needed for the study of particle dispersion in turbulent flows and the associated Lagrangian statistics. Least squares matching is applied in Chapter Four to track in space three-dimensional patterns in small cuboids obtained by laser-induced fluorescence tomography. The method yields fully three-dimensional information on the velocity field, the vorticity field and the field of the rate of strain tensor. In addition, concentration distribution and its derivatives can be determined. Attention is given to presenting the basic theoretical aspects of these new methods as well as practical information needed for their application.