Wetting in porous media

点击翻译按钮获取中文摘要

The characterization and realistic modelling of random disordered materials as diverse as soils, sedimentary rocks, wood, bone, paper, polymer composites, catalysts, coatings, ceramics has been a major problem for physicists, earth scientists and engineers for many years. Nevertheless, the prediction of mechanical and optical properties of the material, as well as the prediction of transport and phase behavior of fluids in porous structures from measures of the morphology and topology is still an unsolved problem. Starting from a microscopic density functional for inhomogeneous fluids in porous media, we aim in this project to determine the dependence of thermodynamic quantities such as the free energy and the wetting behavior of a fluid on the geometry of the substrate. The porous substrate is modelled by overlapping grains (Boolean grain model) and is characterized by structure functions and morphological measures such as volume, surface area, integral mean curvature, and the connectivity of the pores. These measures are known as Minkowski functionals in integral geometry which provides powerful theorems to make the calculus convenient. In particular, the concept of parallel surfaces allows one to determine how physical phenomena such as wetting, capillary condensation and two-phase flow depend on the random structure and the morphology of the pores. The complicated pore structure of an interconnected three-dimensional network of capillary channels of nonuniform sizes and shapes distinguishes a porous medium from any other solid or planar substrate. The project attempts to connect the two main factors, morphology and interfacial effects such as surface energies and wettability, in order to predict phase behavior and transport of fluids in porous media.