Capillary equilibration of trapped ganglia in porous media: A pore-network modeling approach

Ganglia, or bubbles, trapped by capillary forces inside porous materials occur in a wide range of subsurface and manufacturing applications. In geologic CO2 storage, ganglia are desired as they render the injected hydrodynamically immobile. But may evolve dissolution mass exchange across brine, called ripening. fuel cells electrolyzers, water/oxygen must be removed to ensure optimal performance device. both applications, microstructure plays key role how geometry/topology grow/shrink size. This dependence is poorly understood but important for controlling ganglion dynamics. Pore-scale models useful tools probing physics, existing ones either computationally expensive (e.g., CFD) incapable accurately simulating spanning multiple pores pore networks). Our main contribution new pore-network model (PNM) that removes this barrier. The PNM can simulate evolution multi-pore occupying due diffusive transfer ripening an external concentration field. We validate against published microfluidic experiments, 2D direct numerical simulations, analytical solution previously derived authors homogeneous domain. then use study quasi-static growth-shrinkage cycles heterogeneous media. findings constitute our second contribution, generalizing previous theoretical results from 3D-planar microstructures. They include: (1) interfacial area depends approximately linearly on its volume; (2) if throat-to-pore aspect ratio large, growth percolation-like; (3) it small, hitherto unreported intermittent regime precedes percolation, which repeatedly fragment reconnect. These outcomes have implications selecting storage sites designing electrolyzers with finetuned