Wetting transition and fluid trapping in a microfluidic fracture

Journal Article · Mon May 22 00:00:00 EDT 2023 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.2303515120· OSTI ID:1974652

Qiu, Yu ^[1]; Xu, Ke ^[2]; Pahlavan, Amir A. ^[3]; Juanes, Ruben ^[1]

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1. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
2. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, Department of Energy and Resources Engineering, Peking University, Beijing 100871, China
3. Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06511

Immiscible fluid–fluid displacement in confined geometries is a fundamental process occurring in many natural phenomena and technological applications, from geological CO ₂ sequestration to microfluidics. Due to the interactions between the fluids and the solid walls, fluid invasion undergoes a wetting transition from complete displacement at low displacement rates to leaving a film of the defending fluid on the confining surfaces at high displacement rates. While most real surfaces are rough, fundamental questions remain about the type of fluid–fluid displacement that can emerge in a confined, rough geometry. Here, we study immiscible displacement in a microfluidic device with a precisely controlled structured surface as an analogue for a rough fracture. We analyze the influence of the degree of surface roughness on the wetting transition and the formation of thin films of the defending liquid. We show experimentally, and rationalize theoretically, that roughness affects both the stability and dewetting dynamics of thin films, leading to distinct late-time morphologies of the undisplaced (trapped) fluid. Finally, we discuss the implications of our observations for geologic and technological applications.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0018357
• OSTI ID: 1974652
• Alternate ID(s): OSTI ID: 2471949
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 22 Vol. 120; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of Sciences
• Country of Publication: United States
• Language: English