Suppressing viscous fingering in structured porous media

Harris Sajjad Rabbani, Dani Or, Ying Liu, Ching Yao Lai, Nancy B. Lu, Sujit Sankar Datta, Howard A. Stone, Nima Shokri

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)4833-4838
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number19
DOIs
StatePublished - May 8 2018

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Analytical model
  • Direct numerical simulation
  • Microfluidics
  • Structured porous media
  • Suppressed viscous fingering

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