Extending microscopic velocity measurement techniques to non-aqueous fluids in porous media systems

The study of immiscible fluid flows in porous media is essential for understanding complex interactions across natural, biological, and engineering systems, particularly how interface interactions impact macroscopic flow behavior. This thesis focuses on developing experimental methodologies to extend micro-Particle Image Velocimetry (µPIV) applications to non-aqueous fluids, a domain traditionally confined to water-based systems due to the lack of suitable seeding particles for non-aqueous environments. The research is structured around three main objectives: First, it aims to adapt commercially available fluorescent particles from aqueous suspensions to immiscible fluids like oleic acid, ensuring that their dynamic and optical properties remain. This adaptation involves developing a transfer methodology that maintains particle integrity and homogeneous suspension. Second, the study validates these adapted particles through controlled µPIV experiments within well-characterized rectangular microfluidic channels. It compares the behavior of particles in oleic acid against those in water and existing literature to conclude consistency and reliability. Third, the thesis explores the dynamics of single- and multiphase flows in micromodels that simulate coupled free-flow and porous media systems, focusing on differences in flow behavior, viscosity effects, and velocity profiles at the interface between the two compartments. By bridging critical gaps in experimental protocols for non-aqueous fluids, this research not only enhances the utility of µPIV in diverse fluidic environments but also contributes to a deeper understanding of microscale flow dynamics under multiphase conditions.