Chapter 15 - Fluorescence imaging techniques: Application to measuring flow and transport in refractive index-matched porous media

Abstract

This chapter is part of an extensive research in laboratories to understand the nature of the microscopic flow and transport processes within porous media. A novel non-intrusive imaging approach has been used to observe the pore-scale flow and transport behavior at high resolution and high accuracy. This chapter reports on: fluorescent particle tracking velocimetry and concentration imaging techniques, direct experimental evaluation of dispersive fluxes and dispersion coefficients, estimates of representative elementary volume (REV), correlations of velocity and concentration results within the porous medium, and 3-D plots of results to gain insights to the pore-scale flow and transport processes. The overall objective is to use these findings toward gaining an understanding of chemical flow and transport in a porous medium and, as a result, provide the basis for improved modeling of these processes. Traditionally, there have been three different approaches to the modelling of flow and transport in porous media. The first approach is a statistical method treating the porous media as a random structure. The second is a geometrical approach assuming a similar geometry to the porous media under study to solve the conservation equations. The third approach (continuum) is a volume averaging procedure that helps to describe porous medium transport in terms of macroscopic rather than microscopic scale variables. All three approaches result in undetermined parameters that must be evaluated from experiments.