High-speed NMR imaging of capillary action in thin nontransparent porous media

An improved High-Speed NMR profiling method is introduced that enables to measure capillary action in thin, non-transparent porous media. Liquid profiles can be measured as fast as 10 ms with a spatial resolution of 14.5 µm. Capillary absorption of microliter-sized droplets into non-transparent nylon-6,6 porous membranes was studied. In nylon-6...

Numerical modelling and experimental assessment of concrete spalling in fire

In this paper, the phenomenon of spalling of concrete in fire has been studied using a numerical model. Spalling is the violent or non-violent breaking off of layers or pieces of concrete when it is exposed to high temperatures as experienced in fires. The types and mechanisms of spalling have been explained. A numerical model has been developed...

The edge-based face element method for 3D-stream function and flux calculations in porous media flow

We present a velocity-oriented discrete analog of the partial differential equations governing porous media flow: the edge-based face element method. Conventional finite element techniques calculate pressures in the nodes of the grid. However, such methods do not satisfy the requirement of flux continuity at the faces. In contrast, the edge...

A direct method for the identification of the permeability field based on flux assimilation by a discrete analog of Darcy's law

Inverse models to determine the permeability are generally based on existing forward models for the pressure. The permeabilities are adapted in such a way that the calculated pressures match the specified pressures in a number of points. To assimilate a priori knowledge about the flux, we introduce the 'flux assimilation method', which is based...

Three-phase flow analysis of dense nonaqueous phase liquid infiltration in horizontally layered porous media

We considered dense nonaqueous phase liquid (DNAPL) infiltration into a water-unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. DNAPL is the intermediate-wetting fluid with respect to the wetting water and the nonwetting air. The layer interface...