Suppressing viscous fingering in structured porous media.

TitleSuppressing viscous fingering in structured porous media.
Publication TypeJournal Article
Year of Publication2018
AuthorsRabbani, HSajjad, Or, D, Liu, Y, Lai, C-Y, Lu, NB, Datta, SS, Stone, HA, Shokri, N
JournalProc Natl Acad Sci U S A
Volume115
Issue19
Pagination4833-4838
Date Published2018 05 08
ISSN1091-6490
Abstract

Finger-like protrusions that form along fluid-fluid displacement fronts in porous media are often excited by hydrodynamic instability when low-viscosity fluids displace high-viscosity resident fluids. Such interfacial instabilities are undesirable in many natural and engineered displacement processes. We report a phenomenon whereby gradual and monotonic variation of pore sizes along the front path suppresses viscous fingering during immiscible displacement, that seemingly contradicts conventional expectation of enhanced instability with pore size variability. Experiments and pore-scale numerical simulations were combined with an analytical model for the characteristics of displacement front morphology as a function of the pore size gradient. Our results suggest that the gradual reduction of pore sizes act to restrain viscous fingering for a predictable range of flow conditions (as anticipated by gradient percolation theory). The study provides insights into ways for suppressing unwanted interfacial instabilities in porous media, and provides design principles for new engineered porous media such as exchange columns, fabric, paper, and membranes with respect to their desired immiscible displacement behavior.

DOI10.1073/pnas.1800729115
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID29686067
PubMed Central IDPMC5948996