(343a) Pattern Formation over Deformable Structures in Confined Geometries

Modeling liquid-liquid displacements in complex pore morphologies is an outstanding challenge for oil recovery and for the petroleum industry. In particular, the mechanism for liquid entrapment over deformable structures represents a knowledge gap in our formal understanding of multiphase flows in confined geometries. Hydrodynamical and capillary forces in this class of problems can lead to substantial deformations of the host medium. In turn, these deformations have a considerable effect on oil displacement. Here we propose to systematically examine the displacement of a preexisting layer of oil over carefully designed elastic features so as to understand the effect of deformations on oil entrapment. Experiments are carried out in a Hele-Shaw cell, using casted elastic posts whose axis is perpendicular to the direction of flow and whose base is clamped to a wall of the cell. We employ fast prototyping techniques to tailor the mechanical properties of these posts, which undergo large deformations. Combined to scaling arguments and formal models, these experiments provide insights into the parameters that govern this type of physical process and help rationalize the the formation of complex fingering patterns.