Topographic Control of Order in Quasi-2D Granular Phase Transitions

We experimentally investigate the nature of 2D phase transitions in a quasi-2D granular fluid. Using a surface decorated with periodically spaced dimples we observe interfacial tension between coexisting granular liquid and crystal phases. Measurements of the orientational and translational order parameters and associated susceptibilities indicate that the surface topography alters the order of the phase transition from a two-step continuous one to a first-order liquid-solid one. The interplay of boundary inelasticity and geometry, either order promoting or inhibiting, controls whether it is the granular crystal or the granular fluid which makes contact with the edge. This order induced wetting has important consequences, determining how coexisting phases separate spatially.

Automated summary

Experimental investigation shows that the presence of interfacial tension between a granular liquid and crystal phase on a surface with periodically spaced dimples alters the order of the phase transition. The interplay of boundary inelasticity and geometry controls which phase, either granular crystal or granular fluid, makes contact with the edge. This induced wetting phenomenon has important consequences for the spatial separation of coexisting phases.