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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 65: Granular Matter / Contact Dynamics (joint session DY/CPP)
CPP 65.10: Vortrag
Donnerstag, 15. März 2018, 12:30–12:45, BH-N 333
Simulation and modeling of the frustrated packing in a granular system — •Sára Lévay1, David Fischer2, Ralf Stannarius2, Balázs Szabó3, Tamás Börzsönyi3, and János Török1 — 1Department of Theoretical Physics, BME, Budafoki út 8., H-1111 Budapest, Hungary — 2Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2., D-39106 Magdeburg, Germany — 3Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49., H-1525 Budapest, Hungary
Optimal packings of uniform spheres is a solved problem in two and three dimensions. The two-dimensional ground state can be easily achieved by simple dynamical processes while in three dimensions this is almost impossible.
In a recent work we have shown that in 2+ε dimensions, achieved by a container in one dimension slightly wider than the spheres, the particles organize themselves in a triangular lattice touching either of the sides of the container. When the system is agitated, it evolves slowly towards the potential energy minimum through metastable states.
We show results of DEM simulations and Monte Carlo models which fit the experiments: The dynamics is local and is driven by the optimization of the volumes of 7-particle configurations and by the vertical interaction between touching spheres. Defects in the triangular lattice play an important role in the dynamics as they act as an activation source and help the compaction. The system behaves neither as a 2D nor as a 3D system. Geometric frustration hinders the global optimum.