Regensburg 2010 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

DY: Fachverband Dynamik und Statistische Physik

DY 31: Statistical Physics far from Equilibrium

DY 31.6: Talk

Friday, March 26, 2010, 11:45–12:00, H38

Interfacial tension in a fluid-gas coexistence of wet granular matter — •Klaus Röller and Stephan Herminghaus — MPI for Dynamics and Self-Organization, Bunsenstr. 10, D-37073 Göttingen, Germany

We report on simulations of fluid-gas coexistence in agitated wet granular matter [1,2]. Event-driven molecular dynamics type simulations were performed in three dimensions to study the dependence of the excess energy of the fluid-gas interface (’surface tension’) upon the external driving. The surface tension was determined by applying a time-constant but spatially periodic shear force in the direction normal to the interface, and measuring the corresponding elongation of the initially flat interface [3]. The knowledge of the surface tension was then used to estimate an effective granular viscosity using a deterministic version of the Edwards-Wilkinson equation. An initial sinusoidally elongated configuration of the fluid interface was therefore dynamically relaxing back to its (flat) stationary state with minimal interfacial area. We found that both the surface tension and the granular viscosity are decreasing as the driving energy [2] of the external drive is increased. This result can be viewed as the non-equilibrium analogue to the known dependence of these two physical quantities to temperature in equilibrium statistical physics.

[1] S. Herminghaus Advances in Physics 54, 221 (2005)

[2] A. Fingerle, et al., New J. Phys. 10, 053020 (2008)

[3] K. Roeller, et al., Chaos 19, 041106 (2009)