Liquid–solid-like transition in quasi-one-dimensional driven granular media
Clerc, M.G., Cordero, P., Dunstan, J., Huff, K., Mujica, N., Risso, D. & Varas, G., Nature Phys. 4, 249-254 (2008).
granular matter, crystallization, compressibility
The subject of phases in granular matter is not well understood theoretically. Fluidized granular matter can be obtained by vertically vibrating granular layers. The layers exhibit standing-wave patterns when the system has undergone a solid-liquid-like transition.
Clerc et al. do an experimental and theoretical study of a monolayer of grains subjected to vertical vibration. They confined <math>N</math> hard spheres to a long rectangular enclosure, with width of order of a few particle diameters, and height less than two particle diameters. This provided a quasi-one dimensional environment, because 2D spatial effects are minimized.
The bottom plate of the enclosure was vibrated vertically. At the fluid transition, several clusters formed, but eventually only one large cluster remains. Thus the dynamic equilibrium state of the system is a coexistence of liquid-like and solid-like phases, with a dense cluster of grains surrounded by a fluid of loose particles. Several variations of crystal structure were found in the cluster, including square, triangle, and a combination of the two. In addition, the granular media exhibited a negative compressibility.