Enhanced coarsening induced by pore confinement

The coarsening process is driven by the reduction in interfacial energy density, resulting in an enlargement of the size scale within two-phase systems. It plays a crucial role in the stability and the aging of densely packed arrangements of particles, which are commonly found in alloys, foams, emulsions, supersaturated solutions, etc. It has been shown previously that, when properly confined, such particles undergo the so-called anticoarsening phenomenon, ultimately leading to the one particle-per-pore configuration associated with the arrest of coarsening. In this study, we quantitatively explore the coarsening dynamics of liquid foam confined within the pores of spherical bead packings, where the size of the beads has been adjusted to modify the degree of confinement. We observe that, apart from the final configuration associated with the arrest of coarsening, the more we confine this system within small spaces, the more rapidly it coarsens. Moreover, the broadening of the particle size distribution has an opposite effect with respect to that observed for unconfined systems. This unexpected behavior is shown to arise from the coupling between the liquid trapped at the surface of the grains and the effective liquid volume fraction within the core of the pores.