Development of a two-dimensional liquid species concentration measurement technique based on absorptiometry

A nonintrusive optical technique is developed for species concentration measurements in liquid solutions. The technique is based on absorptiometry and uses digital image analysis to measure quantitatively two-dimensional concentration distributions. The apparatus and calibration procedures are described in detail, and the accuracy and resolution are established in uniform concentration and one-dimensional diffusion experiments. The technique is then applied to measure concentration fields during double-diffusive convection in a Hele-Shaw cell, and good agreement with numerical predictions is obtained. The limitations and possible enhancements of the technique are briefly discussed.