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 Thiyagarajan May 20, 2004 09:24

porous media resistance coefficients

hi all,

iam analysing an airfilter.(porousmedium).for the medium,i calculated resistance coefficients .the permeability given 24 CFM, that i converted into 8584e10 1/sq.meter for viscous coeff.problem is 3D and flow is in x direction. my questions, is my coeff. value is reasonable?. i gave resistance co efficients only in x direction,should i give in other directions? if i need to give,can i use the same value ? thanks for any suggestions. regards Thiyaga.

 Evan Rosenbaum May 20, 2004 12:20

Re: porous media resistance coefficients

Your permeability is not unreasonable for a fairly restrictive filter. If you have x-direction flow only, you should can specify the y and z direction permeabilities to an order of magnitude or two higher than your x-direction value.

 Thiyagarajan May 21, 2004 00:08

Re: porous media resistance coefficients

thank you. as you said, the permeability values in y&z are higher than the value of X, the resistance coefficients in y&z should be lower than the value in x direction, is it so?. what about inertial coefficient, the same way can be used?. looking forward to your suggestion.... regards Thiyaga.

 Evan Rosenbaum May 24, 2004 11:48

Re: porous media resistance coefficients

The permeability inputs to FLUENT should be larger in the y and z directions. This is because the FLUENT input is actually the inverse of permeability. You can also do the same with IRF.

 zhhjll June 21, 2011 18:07

I want to model a micro filter, This filter (membrane) is rectangular (10×5 cm) with the thickness 12e-5. so,I calculate this parameters from Ergun equation which D=1e-6, because of the Micro filter type. is this assumption true??
i think this is very thin filter so there in not flow through in the membrane, in this situation is inertial coefficieant higher in Y direction? or not?when i set y-direction inertial coefficient higher than x-direction got better answer! is this resonable?

I am looking forward to hearing from you.
Sincerely yours

 vittal October 27, 2011 06:24

regarding porous medium

Sir,
I am modelling porous medium.
I know velocity=5.6m/s
pressure=5690 pa
discrete phase model
thicknes of porous medium=0.15mm
porosity =0.95

now how to calculate K and c2?

Quote:
 Originally Posted by Evan Rosenbaum ;112692 Your permeability is not unreasonable for a fairly restrictive filter. If you have x-direction flow only, you should can specify the y and z direction permeabilities to an order of magnitude or two higher than your x-direction value.

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