Measurement methods using holography are non-invasive, whole-field and can be applied in real-time. They are particularly appropriate for experimental validation of current CFD (computational fluid dynamics) codes which have 3-dimensional, transient, irregular geometry capabilities.
In holographic interferometry, the fringes formed by refractive index changes represent lines of constant Mach number in isentropic compressible flows and isotherms in convection. Examples are given of two-dimensional inter-ferograms in these areas, and their quantitative interpretation.
Automatic fringe and data processing is a necessity, and the method is extendable to three dimensions using tomographical reconstruction. These issues are discussed, together with the general question of comparison with flow predictions.
Fluid fields may also be treated on a three-dimensional time-dependent basis, using HCV (holocinematographic velocimetry), a holographic extension of PIV (particle image velocimetry). It is proposeds to run an experiment to measure both fluid and thermal fields, and surface temperatures simultaneously, using HCV or PIV, holographic interferometry and liquid crystal methods respectively.