Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Wetting, Micro and nanofluidics I

CPP 36.4: Talk

Thursday, March 29, 2012, 16:00–16:15, C 264

Liquid transport in wet granular packings — •Ciro Semprebon, Stephan Herminghaus, and Martin Brinkmann — Max Plank Institute for Dynamic and Self Organization, Goettingen

Liquid transport in a static pile of spherical beads can proceed through the formation of a thin wetting film on the surface or through the vapor phase. At sufficiently high surface liquid coverage a wetting film can be formed that percolates through the surface roughness. Assuming a constant effective mobility of this film and stationary flow conditions the local pressure in the film satisfies Laplace's equation with Dirichlet boundary conditions given by the Laplace pressure on the contact line of the bridges. The conductance of the film on a spherical surface in the presence of two bridges can be solved exactly by conformal mapping. Employing a perturbative method we arrive at a simplified model to calculate the matrix elements of the complete conductance matrix for arbitrary bridge configurations. Comparison to finite element methods shows that this approximation is sufficiently precise under certain conditions. The simplified model can be implemented in coarse grained numerical simulations aiming at the liquid transport through large static packings of spherical beads at different liquid saturations.