Darcy flow in porous media and polymer apparent viscosity

2 Darcy flow in porous media and polymer apparent viscosity 

The two most commonly measured rock properties are porosity, (f), and absolute (single-phase) permeability, k. The porosity (or voidage) is the fraction of the bulk volume of the porous sample that is occupied by pore or void spaces. For different types of porous media, the porosity can vary from nearly zero (e.g. certain volcanic rocks) to almost unity (e.g. insulators). The porosity can be measured using a variety of methods, which are described by Dullien (1979). 

The permeability, k, is a measure of the conductivity of the porous medium. It is defined by Darcy s law, which gives a linear relationship for the volumetric flow rate, Q, and pressure drop, AP, as  

The Darcy velocity, m, is defined as the flow rate entering the porous medium, Q, per unit cross-sectional area of the sample  

This is usually related to the average pore velocity (also called the interstitial or superficial pore velocity), i , by  

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