Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 31: Particulate Matter I: From microscopic interactions to collective motion (Focus session)

DY 31.10: Vortrag

Mittwoch, 22. März 2017, 12:30–12:45, ZEU 118

Pattern formation on the brink of granular liquid-gas-like transition — •Andreas Zippelius and Kai Huang — Universität Bayreuth, 95440 Bayreuth, Germany

Granular materials driven far from thermodynamic equilibrium are a rich pattern forming system. For instance, a thin layer of sand grains under vertical vibrations yields Faraday's crispations (stripes, squares, circular rings, etc.). If the particles are slightly wet, so that cohesive particle-particle interactions start to play a role, a different pattern forming scenario arises: Propagating kink-wave fronts and rotating spirals emerge as the granular layer is fluidized.

Here, we report a new class of patterns observed in the vicinity of the liquid-gas-like transition in a cohesive granular layer. It is composed of ordered density-wave fronts propagating continuously along the rim of the container. We quantify the rotation speed and the shape of the fronts by means of high speed photography and discuss the influence of particle-particle interactions and driving parameters on the pattern selection. Finally, we analyze the dynamics of the propagating fronts from the mobility of individual particles to shed light on the pattern forming mechanism.