Capillary equilibrium of bubbles in porous media

Chuanxi Wang, Yashar Mehmani, Ke Xu

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


In geologic, biologic, and engineering porous media, bubbles (or droplets, ganglia) emerge in the aftermath of flow, phase change, or chemical reactions, where capillary equilibrium of bubbles significantly impacts the hydraulic, transport, and reactive processes. There has previously been great progress in general understanding of capillarity in porous media, but specific investigation into bubbles is lacking. Here, we propose a conceptual model of a bubble’s capillary equilibrium associated with free energy inside a porous medium. We quantify the multistability and hysteretic behaviors of a bubble induced by multiple state variables and study the impacts of pore geometry and wettability. Surprisingly, our model provides a compact explanation of counterintuitive observations that bubble populations within porous media can be thermodynamically stable despite their large specific area by analyzing the relationship between free energy and bubble volume. This work provides a perspective for understanding dispersed fluids in porous media that is relevant to CO2 sequestration, petroleum recovery, and fuel cells, among other applications.

Original languageEnglish (US)
Article numbere2024069118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number17
StatePublished - Apr 27 2021

All Science Journal Classification (ASJC) codes

  • General


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