Berlin 2005 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.111: Poster

Montag, 7. März 2005, 15:30–18:00, Poster TU D

Shape of critical fluctuations in LJ-fluids and wet granular media — •Christian Goll ¹ and Klaus Mecke^1,2 — ¹MPI für Metallforschung, Stuttgart — ²Institut für theoretische Physik, Universität Erlangen-Nürnberg, Staudtstrasse 7, D-91058 Erlangen

We present a molecular dynamics simulation of a Lennard-Jones fluid close to the liquid-vapor critical point to study the shape of the fluctuating configurations. Clusters of size R are defined by attaching spheres of radius R at each particle. The shape is measured by Minkowski functionals M_ν of the covered region in space. An effective local cluster shape m_ν is defined which takes all n-point correlations on scales smaller than 2R into account and describes the local structure in an illustrative way (depletion zone, clustering). A possible scaling behavior m_ν∼ R^α_ν is analysed at large lengths R where multi-point correlations become important which are not captured by the scaling of two-point structure function alone. We applied the same simulation and morphometric technique to a shear-induced solid-fluid transition in wet granular matter, where dissipation occurs in a hysteretic nature of a cohesive force induced by adsorbed liquid bridges between the spherical particles. Comparision of the critical morphology with LJ-fluid and with recent x-ray tomography data of wet bead packs are presented.