All, I am modleling the flow through a porous media, can anyone here tell me the methods to determine the resistance of the porous? I checked out a ASTM standard and will try to measure the pressure drop and then calculate the resistance coefficient. Is there an alternative way? I believe some people here are very clear on this issue, hope you can direct me to the right way. Thanks and merry Christmas.

Look for Darcy's law.

Or the Ergun equation.

There has been extensive discussion of this in the chemical engineering literature, usually in an attempt to develop inter-phase drag terms that are valid for *all* phase volume fractions. For example Darcy's law is valid at the point where the solid phase becomes locally connected- usually at anywhere from 30 volume percent upwards, but this also depends on the kinematics of the flow field. Darcy's law is valid at much lower solid volume percent than the maximim packing. And one needs some geometric rule to translate solid phase volume fraction to surface area as this is what really matters. There are whole books on this subject.

One refernce that I have used that combines things like the Ergun equation, Darcy's law, etc. is:

Argwahl, P. K. and O'Neill, B. K., 1988, "Transport phenomena in multi-particle system-1. Pressure drop and friction factors: Unifying the hydraulic-radius and submerged object approaches", Chem. Engng. Sci., v. 43, p. 2487-2499.