IMAGE-FORMING OPTICAL TECHNIQUES IN HEAT-TRANSFER - REVIVAL BY COMPUTER-AIDED DATA-PROCESSING

Increasing possibilities of computer-aided data processing have foster ed a revival of image-forming optical techniques in heat and mass tran sfer as well as in fluid dynamics. Optical measuring techniques can pr ovide comprehensive and detailed information on the formation of phase interfaces, particle movement, or the size distribution of droplet sw arms. Holographic interferograms contain full information, not only ab out boundary layers restricting transport processes, but also on local coefficients of heat and mass transfer. Laser-induced fluorescence pr omotes a better understanding of combustion processes by conveying ins ights into the con-centration and the temperature in and around a flam e. For describing complicated phenomena in fluid dynamics or in heat t ransfer by computer programs, global experimental information is not s ufficient. Optical techniques provide local data without disturbing th e process and with a high temporal resolution. By using the results of optical measuring techniques, it is possible to improve computer prog rams that describe physical processes. Optical techniques are also ver y sensitive touch-stones for checking the quality of such programs.