Laser induced fluorescence tomography in passive and reactive scalar fields

We present a novel technique for calculating velocity fields out of non-reactive passive scalar fields and also first results of visualization of high concentration gradient interfaces in a fast mixing process with a pH-sensitive reactive scalar in small and large scale observation. In a non-reactive turbulent shear flow a correlation technique is used to calculate 3D velocity fields out of the measured grey level distribution in the scalar concentration field. The method allows in addition to determine the rate of strain tensor without performing any calculated differentiations. In the second part of the paper the pH-dependence of the fluorescence of disodium fluorescein is used for the visualization and determination of the high concentration gradient surfaces at which chemical reactions take place. This surfaces are of high interest for mixing sensitive chemical reactions and competitive consecutive chemical reaction systems.