Impact of intergranular bonds on morphology transition of two-phase fluid-induced deformation

Multiphase flow in cohesive granular materials underlies various natural and industrial processes, yet the role of intergranular bonds is commonly overlooked. Herein, we probe the morphodynamics of two-phase fluid-induced deformation in a cohesion-tunable bonded granular medium. We illuminate a first-ever pattern diagram in the phase space of varying flow conditions and cohesion levels, with five distinct patterns spanning from fracturing with bond breakage to fingering without grain motion. The competition between skeleton cracking and fluid percolation results in a striking nonmonotonic trend between injection pressure and cohesiveness. We characterize these pattern transitions via dimensional analysis, effectively quantifying the balance between capillary, viscous, and cohesive forces at play. © 2025 American Physical Society.