Fingering patterns in hierarchical porous media

TL;DR

This study explores how hierarchical pore structures in porous media influence fluid displacement, revealing that secondary structures can suppress fingering and providing a phase diagram to characterize these effects.

Contribution

It introduces a novel phase diagram based on a scaling parameter to analyze fingering dynamics in hierarchical porous media, advancing understanding of multiphase flow behavior.

Findings

Secondary porous structures can suppress fingering.

A phase diagram characterizes fingering dynamics.

Hierarchical structures influence flow stability.

Abstract

Porous media with hierarchical structures are commonly encountered in both natural and synthetic materials, e.g., fractured rock formations, porous electrodes and fibrous materials, which generally consist of two or more distinguishable levels of pore structure with different characteristic lengths. The multiphase flow behaviours in hierarchical porous media have remained elusive. In this study, we investigate the influences of hierarchical structures in porous media on the dynamics of immiscible fingering during fluid-fluid displacement. By conducting a series of numerical simulations, we found that the immiscible fingering can be suppressed due to the existence of secondary porous structures. To characterise the fingering dynamics in hierarchical porous media, a phase diagram is constructed by introducing a scaling parameter, i.e., the ratio of time scales considering the combined effect of characteristic pore sizes and wettability. The findings present in this work provide a basis for further research on the application of hierarchical porous media for controlling immiscible fingerings.