(Unidad asociada CSIC-UPC)

Abstract: In this study, we experimentally determine the relevance that a sharp interface zone between two different macroscopic porous mediums, with contrasting transport properties, has on mixing. For that purpose we studied the evolution of the concentration of a colored product generated when two colorless reactants are mixed. This colored product is quantified by image processing, using pixel-by-pixel calibration, to turn light intensities into concentrations. The experiments were performed in a 60 cm long laboratory column filled with glass beads, following four different setups combining coarse and fine glass beads sizes. These four combinations include two bilayer coarse-fine glass beads size distribution schemes and, for comparison purposes, two homogeneous glass beads size distributions. The evolution of the reaction front throughout the column show significant differences among the different combinations performed. Regarding the homogeneous scenarios, in the coarse medium is generated more concentration of the product than the fine mediums.  On the other hand, in bilayer schemes, it is explicitly observed more accumulation of the product concentration when flow goes from coarse to fine layer than when it goes the other way around.