Review of Literature

Interferometry

Optical methods have been employed sporadically for heat transfer measurements over the past 50 years. The convenience of lasers as light sources and computers for data acquisition and processing has resulted in a resurgence of this technique in the past decade. Recent developments have been summarized in a special issue of Optics & Laser Technology (February, 1999) on "Optical Methods and Data Processing in Heat and Fluid Flow". In more general setting. new and novel measurement technologies can be seen in the proceedings of the biennially held International Symposium on Flow Visualization and the Pacific Symposium on Flow Visualization and Image Processing. A survey of interferometry as applied to natural convection problems in presented below.
An early review of optical methods in heat transfer has been presented by Hauf and Grigull [1]. Chu and Goldstein [2] have reported a study of turbulent convection in a horizontal layer of water for the classical Rayleigh-Benard problem. Mach-Zehnder interferometer was employed by the workers for flow visualization. Lewis et al [3]. have investigated the development of mixing-layers in laboratory experiments concerning salt-stratified solutions that are initially stable, but are destabilized by a temperature difference in the vertical direction. Goldstein [4] has surveyed optical technologies for flow and temperature measurement. Lauterborn and Vogel [5] have reviewed the status of optical techniques in fluid mechanics. Mayinger [6, 7] has reviewd image forming optical techniques in heat transfer and computer-aided data processing. Tolpadi and Kuehn [8] have reported a computational and experimental study of a three-dimensional temperature field in an asymmetric geometry. The heat transfer problem involves conjugate conduction-convection and the thermal field in both the solid and fluid phases have been visualized using interferometry. These authors have compared the performance of several reconstruction algorithms applied to experimental data against the numerical solution. The Grid method was found to have the greatest accuracy. Naylor and Tarasuk [9] have presented a computational technique for processing inerferograms that are seen in buoyancy-driven convection. Muralidhar et al. [10] have studied the transient natural convection in a square cavity in the intermediate Rayleigh number range using a Mach-Zehnder interferometer. Evalutels-Lehnoff et al. [11]. Chandrasekhara et al. [12] have discussed a high-speed phase-locked interferometry system that has been designed and developed for real-time measurements of dynamic stall flow over a pitching aerofoil. Zhonag and Squire [13] have used interferometry to evaluate organized structures in high-spped flow past a circular cylinder. They have reported the similarities between compressible and incompressible wakes as well as similarities in the turbulent structures. Dupont et al. [14] have discussed the use of electronic speckle interferometry for visualizing isotherms as well as streamlines in a Rayleigh-Benard configuration. Dietz and Balkowski [15] have discussed the estimation of refraction errors in two-dimensional supersonic boundary layers. Most recently, Optical methods for flow and heat transfer have been reviewed by Lehner and Mewes [16].