What Is a Porous Medium?
A porous material consists of a solid structure (porous matrix) with voids (pores) filled with a liquid or gas. Porous materials are found in all sizes and across a wide range of applications - from nanomaterials to porous reactors, for cooling of electronic components to large scale geotechnical applications. What they all have in common is that the total size of the material is much bigger than the mean pore diameter, so that a macroscopic approach must be used to model the applications.
Figure 2-1: Flow through porous structures.
If it is possible to calculate averaged values from the simulation on a microscopic scale (Figure 2-1), which are also representative for any other section, the modeled section is called a representative elementary volume (REV). Two variables mainly characterize the porous material: The porosity describes the ratio of void/pore volume to total volume
and the permeability κ(m2) specifies the ability of a fluid to pass through it.