Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Pattern formation in colloidal and granular systems I

DY 24.6: Talk

Thursday, March 26, 2009, 16:00–16:15, ZEU 255

Phase diagram of wet granular material under vertical vibrations — •Kai Huang, Klaus Röller, and Stephan Herminghaus — Max Planck Institute for Dynamics and Self-organization, Bunsenstr.10, 37073 Göttingen, Germany

The phase diagram of vertically vibrated wet granular matter is investigated by both experiments and simulations. We find a critical point where the coexistence (C) regime of the fluid (F) and gas (G) phases terminates. The energy driven F-C transition is found to scale with the rupture energy of a liquid bridge if the corresponding vibration amplitude(A) is less than particle diameter(d). This is in good agreement with our simulations. Close to the F-G transition line, the variation of the size of the gas bubble with vibration amplitude shows a hysteretic behavior. Within the hysteresis loop, we observe temporary gas bubbles with strong fluctuations in size. The F-G boundary is shown to have an interfacial tension and non-trivial wetting behavior at container walls. Focusing on the solid (S)- F transition line, we find that the fluidization is a surface melting process. This is demonstrated by detecting the mobility of ruby tracers utilizing ruby fluorescence. This as well agrees with our simulation results.