Berlin 2018 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 61: Granular Matter / Contact Dynamics (joint session DY/CPP)
DY 61.11: Talk
Thursday, March 15, 2018, 12:45–13:00, BH-N 333
Frustrated packing in a granular system confined in a 2+ε dimensional box — •David Fischer1, Sára Lévay2, János Török2, and Ralf Stannarius1 — 1Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany — 2Department of Theoretical Physics, BME, Budafoki út 8., H-1111 Budapest, Hungary
Packing of spheres in three dimensions necessarily involves geometrical frustration. The locally optimal tetrahedral packing is not space-filling. In contrast, the close-packed equilateral triangular lattice optimizes the packing of disks in a two-dimensional plane both globally and locally.
We show experimentally that inside a container of a width only slightly wider than the diameter of the spheres, the particles organize themselves in a quasi-triangular lattice touching either the front or back wall of the container. Under appropriate agitation (harmonic vertical vibrations) the system can be driven remarkably close to its ground state. Nevertheless, perfect order is practically never reached.
We demonstrate that the system can be described by 13 local 7-particle configurations and that the volume occupied by those configurations plays a key role in the redistribution dynamics of the system. Our studies offer insights into both the influence of geometrical constraints on random granular packing and a descriptive example of frustrated ordering, comparable to order in antiferromagnetic Ising spin models.