The origin of optical methods for fluid flow investigations appears to be nontraceable. This is no matter for surprise. After all seeing provides the most direct and common way for humans to learn about their environment. But at the same time some of the most sophisticated methods for doing measurements in fluids are also based on light and often laser light. A very large amount of material has been published in this area over the last two decades. Why then another publication? Well, the field is still in a state of rapid development. It is characterised by the use of results and methods developed within very different areas like optical physics, spectroscopy, communication systems, electronics and computer science, mechanical engineering, chemical engineering and, of course, fluid dynamics. We are not aware of a book containing both introductory and more advanced material that covers the same material as presented here. The book is the result of a compilation and expansion of material presented at a summer school on Optical Diagnosticsfor Flow Processes,held at RiS0 National Laboratory and the Technical University of Denmark in September 1993. The aim of the course was to provide a solid background for understanding, evaluating, and using modem optical diagnostic methods, addressing Ph. D. students and researchers active in areas of fluid flow research. The disciplines represented by the participants ranged from atmospheric fluid dynamics to biomedicine.

Optical methods are now used routinely for the measurement of velocity, concentration, temperature, and other parameters in wide-ranging areas of industrial research and design such as IC engines, turbines, and combustors. Recent advances such as the use of high-resolution CCD cameras and the extension of flow mapping to three dimensions, make optical tools such as particle image velocimetry increasingly viable for use in the industrial environment. This excellent book presents new developments in optical diagnostic techniques in heat and fluid flow and offers an unparalleled opportunity for industrialists and academic researchers to exchange ideas. CONTENTS INCLUDE: Comparison of injector sprays for gasoline direct-injection engines The design, development, and preliminary results from a high-speed, optically accessed, single cylinder engine The reflected spectrum of complex multi-layered inhomogeneous highly scattering medium Development of full volume digital holography for particle measurement Improved liquid crystal thermography by using true-colour image processing technology Development of an optical measuring technique for the study of acoustical phenomena Spatio-temporal reconstruction of the unsteady wake of axisymmetric bluff bodies via time-recording DPIV Application of particle image velocimetry to helicopter vortex interactions Pulsed laser particle image velocimetry using a fibre-optic delivery system Automated fringe analysis for profilometric mass-transfer experiments.

The General Assembly of the International Union of Theoreti cal and Applied Mechanics decided in Cambridge, United King dom, in 1982 to arrange the Symposium on Optical Methods in the Dynamics of Fluids and Solids. This decision was stimu lated by the fact that optical diagnostic methods are a more and more important tool in experimental mechanics. In contrast to the foregoing Symposium in Poitiers. 1976, which was devoted exclusively to optical methods in the me chanics of solids, it was a fruitful idea to bring together during the present Symposium scientists engaged in optical methods in the dynamics of all phases. It was proposed by the International Scientific Committee of the Symposium that contributions in experimental fluid dynamics should deal with transition from laminar to turbu lent flow, compressible fluid flow including high temperatu re flow, non-equilibrium phenomena in fluid dynamics and the interaction of fluid flow with solid boundaries and bodies. As regard. the mechanics of solids, the contributions should deal with the application of optical methods in the wave propagation in shock loaded bodies, in phenomena connected with the fracture mechanism, in nonstationary Vibrations of elements and parts of systems and in nonstationary strains in structures. The International Scientific Committee preferred to avoid invited lectures and in cooperation with the National Com mittees of IUTAM called for contribution from individual countries.