Topological transitions in unconfined vibrated concentrated suspensions

•Vertical vibration of concentrated particulate suspensions yields craters, mounds and spheres.•Topological changes are caused by periodic jamming transitions in the suspension.•Ratio of the sedimentation time and the period of the oscillation is a key dimensionless group. Vertical vibration of a concentrated suspension of spherical particles in a liquid yields an array of intriguing behaviors. Here we report new results for unconfined suspensions on a vibrating plate, and show that under certain conditions the suspension forms depressions or craters, while in other conditions it gathers to form a mound, a conical “volcano”, or even a sphere that sits just above the vibrating plate. This behavior results from a jamming transition as the plate accelerates upward, followed by unjamming as it accelerates downward. The ability of periodic jamming and unjamming to induce topological transitions is confirmed by scaling analysis, and sphere formation is further examined by numerical simulation of a suspension with an acceleration-dependent viscosity. [Display omitted]