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May 12, 2004, 22:50 
viscous resistance coefficients in Porous media

#1 
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I have a question about setting resistance coefficients in a porous media problem.
Based on my experiment, I knew some info on pressure drop, so I calculated permeability(alpha called in Fluent 6.1). In Fluent 6.1 pannel, is it correct that i put 1/alpha as a resistance coefficients? The value is 8682372. (alpha=0.000000115). I got a converged solution, but I am not sure whether I did it right. Last question is about what the physical/superficial velocity is in perous media. I read a old manual(6.0), which did not explain well about physical velocity. Which is recommeded to set a porous media problem? Million thanks in advance. cho 

May 13, 2004, 11:44 
Re: viscous resistance coefficients in Porous medi

#2 
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cho:
settting up of coeff is explained very well in the fluent manual. please read 6.19.6 User Inputs for Porous Media carefully  you dont need anyones advice on that  if you have specific question about the content of this page, let know. now about physical vel  the way i understand it is as follows : please some one correct me if i am wrong. porous media is basically just a momentum sink and generally in all the porous media related equations, we need superficial vel. that is not the actual vel with which you fluid is moving in the pores  but physical velocity kind of gives you a measure of that actual fluid velocity. 

May 14, 2004, 10:50 
Re: viscous resistance coefficients in Porous medi

#3 
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How about your local pressures calculated in Fluent? Match with experimental?


June 21, 2011, 18:08 

#4 
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zohreh
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Location: Tehran
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I want to model a micro filter, This filter (membrane) is rectangular (10×5 cm) with the thickness 12e5. so,I calculate this parameters from Ergun equation which D=1e6, 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 ydirection inertial coefficient higher than xdirection got better answer! is this resonable? I am looking forward to hearing from you. Sincerely yours 

September 14, 2013, 06:18 
hello guys,

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Anonymous
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I have trouble finding the alpha and beta values for modelling plasma (blood ) flow through a porous media which acts as the filter. All i have is the porosoity report and material properties.
Is it possible to calculate the inertial and viscous coefficients ? 

September 16, 2013, 02:34 

#6 
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AA Azarafza
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@dreamlifter747
I suppose that you should consider your own experimental setup to extract the interest variables. Refer to Fluent theory guide.
__________________
Regard yours 

September 16, 2013, 03:37 

#7 
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The superfical velocity = volume flow rate / flow area of porous media.
physical velocity = superfical velocity / porosity. If you have some experiment data of pressure drop, you can fit them by a quadratic function: dP = a*v^2 + b*v + c. (v is superfical velocity) The inertial coeff. = 2*a/density; viscous coeff. = b/dynamic viscosity. 

April 22, 2014, 01:46 

#8 
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@quantities
I am getting a negative value for permeability since my graph has a negative linear coeff. and I cannot input a negative value for permeability in the porous media should I just neglect it being negative? Thank you in advance. will 

December 15, 2014, 16:15 

#9  
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isaac
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Quote:
tnx about your this comment can u say to me what is your source?for this note? 

December 15, 2014, 21:01 

#10 
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François Grégoire
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Look at equation (72) here: https://www.sharcnet.ca/Software/Flu...sect_porous_mv
In quantities' post, corresponds to in (72) and corresponds to . I'm not sure about the in quantities's equation. 

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