# Dresden 2020 – wissenschaftliches Programm

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# DY: Fachverband Dynamik und Statistische Physik

## DY 50: Granular Matter and Granular Dynamics II

### DY 50.3: Vortrag

### Donnerstag, 19. März 2020, 10:30–10:45, ZEU 160

Applyig Edwards’ theory for a 2+є dimensional frustrated granular system — •Sára Lévay^{1}, David Fischer^{2}, Ralf Stannarius^{2}, Tamás Börzsönyi^{3}, Ellák Somfai^{3}, and János Török^{1,4} — ^{1}Budapest University of Technology and Economics, Budapest, H. — ^{2}Otto-von-Guericke-University, Magdeburg, G. — ^{3}Wigner Research Centre for Physics, Budapest, H. — ^{4}MTA-BME Morphodynamics Research Group, Budapest, H.

Despite the inherent athermal features of granular materials, treating jammed granular systems in analogy to thermal equilibrium statistical mechanics was proposed by Edwards by using a volume ensemble of equiprobable jammed states, and introducing a configurational temperature named compactivity. Since then this concept was successfully used to derive the volume fraction of random loose and random close packing. We use Edwards’ theory to describe a 2+є dimensional frustrated system of monodisperse spherical particles. This is a flat cuboid cell at the transition between two and three dimensions: slightly thicker than the diameter of a particle. If the container is only slightly larger than the particle diameter, the optimal packing is a triangular lattice in two dimensions and particles are building alternating stripes in the third direction. It was observed that the system does not reach its ground state using mechanical agitation by shaking. In order to understand this puzzle we performed analytic calculations of the volume and the expected number of specific local configurations of particles in our system according to Edwards’ theory, and successfully matched them with numerical simulations and experiments.