Analysis of mixing dynamics and the development of miscibility in microchannels

We investigate fluid miscibility and mixing dynamics within microchannels using both experimental and computational approaches. Microchannels serve as analogs for the pores within subsurface porous media and offer a controlled environment to analyze the effects of injection velocity, fluid viscosity, and the presence of surface asperities on fluid behavior at the microscale. Experimental tests were conducted using a custom-fabricated microcapillary loop, where miscible fluids with different viscosities were injected through Y-shaped inlets, allowing for the observation of mixing and miscibility development along the channel. Complementary computational fluid dynamics simulations using OpenFOAM provided quantitative insights into the flow dynamics, particularly focusing on the Reynolds number, injection velocity, viscosity ratios, and the effects of asperities in the flow channel on mixing efficiency. The results indicate that larger injection velocities and increased viscosity ratios lead to delayed mixing. The introduction of pore-scale asperities significantly enhances mixing by inducing flow irregularities and complex flow patterns. This research advances our understanding of fluid interactions in confined environments and offers practical implications for optimizing microfluidic device designs and improving fluid injection processes in industrial applications.