Fluid-fluid phase separation in a soft porous medium

Abstract

Various biological and chemical processes lead to the nucleation and growth of non-wetting fluid bubbles within the pore space of a granular medium, such as the formation of gas bubbles in liquid-saturated lake-bed sediments. In sufficiently soft porous materials, the non-wetting nature of these bubbles can result in the formation of open cavities within the granular solid skeleton.Here, we consider this process through the lens of phase separation, where thermomechanics govern the separation of the non-wetting phase from a fluid-fluid-solid mixture. We construct a phase-field model informed by large-deformation poromechanics, in which two immiscible fluids interact with a poroelastic solid skeleton. Our model captures the competing effects of elasticity and fluid-fluidsolid interactions. We use a phase-field damage model to capture the mechanics of the granular solid. As a model problem, we consider an initial distribution of non-wetting fluid in the pore space that separates into multiple cavities. We use simulations and linear-stability analysis to identify the key parameters that control phase separation, the conditions that favour the formation of cavities, and the characteristic size of the resulting cavities.

The crucial role of elasticity in regulating liquid-liquid phase separation in cells

“…Cells are multicomponent mixtures, continuously involved in chemical reactions, and contain a sea of elastic network that resists deformation; this makes developing an all-encompassing physics-based quantitative model for LLPS a formidable task. Cleverly designed synthetic polymer-based systems have provided a simpler setup to experimentally and theoretically study various aspects of phase separation including the effects of elasticity, network size, capillary forces, and cooling rate [6][7][8][9][10][11]. Previously we have explained through quantitative modeling that elastic resistance imposed by the medium can constrain the growth of droplets [12].…”