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 pato February 7, 2012 07:11

which is correct

Hi!
i´m have some problems to set up the proper permability and resistance loss coefficient of my porous media. Actually i found different answers about how these coefficient are expressed, having different solutions with both of them.

one is:

You have to input a POROSITY, PERMEABILITY COEFFICIENT and RESISTANCE LOSS COEFFICIENT.

The porosity is simply the % VOID of the region.

The Permeability Coeff governs low speed viscous losses. If Erguns equation is to be adopted, this term can be calculated as:

Kperm = [(Dp^2)*(epsilon^3)*(S^2)]/[150*(1-epsilon)^2]

where:
Dp = equivalent spherical diameter of particle
= 6*(Volume of Particle/Surface Area of Particle)
S = sphrecity (measure of how spherical) = ((pi^1/3)*(6Vp)^2/3)/Ap

The Resistance Loss term governs inertia effects and can be calculated as:

KLoss = 2[1.75*(1-epsilon)/(S*Dp*(epsilon^3)]

and the other is an aproximation which says:

Res.Loss COeff= 2*(0.55/k^0.5)* porosity^2

where 0.55/k^0.5 = form coefficient

both ways have as a result very different values of Kperm and Kloss.
could someone help me? has each Kpermeability necesarily an associated and unique Rloss?

thank you

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