Analysis of Flow and Transport in Refractive Index Matched Porous Media

In the present work a novel method for the measurement of flow and transport in porous media has been developped. Through the employment of particularly applicative solids, liquids and fluorescent dyes and the application of a method for the highly precise matching of refractive indices, the dynamics of the dye distribution inside a threedimensional porous medium could be determined with a high temporal and spatial resolution using planar laser-induced fluorescence. For the data analysis specifically adapted algorithms for image preprocessing have been developed and a method for local parameter estimation has been adapted and significantly enhanced for the present application. The performed measurements represent the first simultaneous estimation of the longitudinal and both transversal hydrodynamic dispersion coefficients. Whereas for the longitudinal dispersion a previously known power-law could be confirmed, the significantly different behavior of the transversal dispersion in vertical and horizontal direction has been observed for the first time. Furthermore the measurements provide the first direct evidence for the existence of stagnant zones in the liquid phase, which have an important effect on the dispersion and are a potential explanation for the power-law behavior. Finally the described technique was used for the first highly resolved visualization of the flow of two immiscible liquids in a threedimensional porous medium.