Collapse of a granular raft: particle-scale features on a continuum model*

Particles floating on a fluid-fluid interface can self-assemble and form a raft due to capillary interactions. In recent work, we experimentally observed that granular rafts under a bi-axial compression fail in two distinct modes: individual particle expulsion from the interface and collective folding or creasing. A preliminary continuum model related the failure modes with particle sizes and density difference between the upper and lower fluid. But it failed to capture the effect of interfacial tension or particle wettability, both of which were observed to affect raft failure as well as raft formation. To rationalize these observations, we construct a revised continuum model including the effect of particle position for the shape of the granular raft along the fluid-fluid interface. In this talk, we will present how the effect of single particle position changes the failure mode.