Holographic Interferometric Study of Heat Transfer in Rectangular Cavities

Optical techniques like interferometry, shadowgraphy and schlieren photography find common use in investigations1 of fluid flow and heat transfer. The change in refractive index of the fluid caused by temperature and density changes is the basis of these methods. These non-intrusive probes have several advantages over mechanical probes such as, very high spatial and temporal resolution, absence of probe induced perturbations, etc. Mach-Zehnder interferometers are frequently employed for analysing heat transfer in fluids. But the need to maintain nearly identical path length in the two limbs (hence requires two identical cells with optically flat windows, one cell being used for compensation) has limited its application considerably. Holographic interferometry, on the other hand is especially well suited to studies with transparent fluids since there is no need for special windows or cells.