Berlin 2005 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 24: Granular Matter
DY 24.2: Vortrag
Samstag, 5. März 2005, 14:30–14:45, TU H2032
Solid - fluid transition of a monolayer of particles: Experiments — •Andreas Götzendorfer1, Jennifer Kreft1,2, Christof Krülle1, and Ingo Rehberg1 — 1Experimantalphysik V, Universität Bayreuth — 2Center for Nonlinear Dynamics, University of Texas at Austin
We study the fluidization of a monolayer of glass beads in a shaken annular container. In our experiment we superpose a vertical vibration with an angular oscillation around the axis of symmetry such that every point of the support follows a circular trajectory. As long as the maximum acceleration of the support is lower than the acceleration of gravity, the monolayer performs a sick-slip motion with respect to the support and moves as a solid block. Forcing with maximum accelerations above 1.5 times the acceleration of gravity fluidizes the monolayer completely. That means the individual particles jump high and the particle concentration is much lower than in the condensed phase. At intermediate forcing intensity we find that the two phases coexist. A block of condensed material travels around the ring at velocities of several cm/s, whereas in the rest of the ring the granular material is in a gas like state. The size of the condensed block and its speed vary with the forcing intensity.