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DY: Fachverband Dynamik und Statistische Physik

DY 24: Poster I

DY 24.47: Poster

Wednesday, March 28, 2007, 16:00–18:00, Poster D

The Phase Diagram of Wet Granular Matter under Vertical Agitation — •Axel Fingerle, Klaus Röller, and Stephan Herminghaus — MPI for Dynamics and Self-Organization, Bunsenstr. 10, D-37073 Göttingen, Germany

Wet granular matter has numerous industrial applications and there is some phenomenological knowledge about soil liquefaction caused by earth quakes for such systems. We provide physical insight in the critical behavior of wet granular matter under vertical agitation. The minimal capillary model [1,2] has been applied to simulations, and a continuum descriptions for wet granular matter has been derived. We could reveal two distinct mechanism for phase transitions far from thermal equilibrium, which are confirmed by experiments: The solid-fluid transition sets in when the vertical acceleration Γ of the plates confining the wet granulate is strong enough to overcome the cohesion force of the interstitial liquid phase. The fluid-gas transition defines a critical line at a mean squared velocity < v² > of the shaking, which is proportional to the surface tension of the wetting liquid. Furthermore, there are two disjoint domains of solid-gas and fluid-gas coexistence in the Γ-v-plane. We introduced dynamical order parameters to quantify the states of wet granular matter and derived a local equation of state. With these results and the piecewise symplectic structure of the capillary model, wet granular matter serves as a paradigmatic system for nonequilibrium physics with favorable mathematical properties.

[1] S.H., Adv. Phys. 54, 221 (2005).

[2] A.F. and S.H., Phys. Rev. Lett. 97, 078001 (2006).