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porosity and porous media

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Old   May 27, 2014, 15:17
Default porosity and porous media
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Ebrahim
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hi
I was wondering to know that if anyone could tell me in which equation porosity is used for modelling of porous media by Fluent and what is its role?
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Old   May 28, 2014, 09:19
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Manuel Díaz Brito
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Go to section 7.2.3 of the FLUENT User Guide on Porous Media and also 1.2.2. on the FLUENT Theory Guide. Ultimately porosity parameters are "fed" into the momentum equations as a body force term acting like a "sink" of momentum, according to the viscous and inertial resistances set.
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Old   May 28, 2014, 13:21
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Quote:
Originally Posted by MDB View Post
Go to section 7.2.3 of the FLUENT User Guide on Porous Media and also 1.2.2. on the FLUENT Theory Guide. Ultimately porosity parameters are "fed" into the momentum equations as a body force term acting like a "sink" of momentum, according to the viscous and inertial resistances set.
Beside of all "MDB" mentioned, porosity is used to calculate several important effective properties such as mass diffusivity (species mass transport), thermal conductivity(energy equation), UDS diffusivity and even more I can't recall at the moment.
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Old   May 29, 2014, 13:20
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Hi
Thank you for your suggestions
I have read the manual, but there is another problem:
As manual said for steady flow in porous media, porosity is not be considered in the momentum equation and the modelling, but why the role of permeability is insignificant in steady flow? (for different viscous resistance pressure contour and volume fraction of fluid are the same)
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Old   May 29, 2014, 17:00
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Quote:
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Hi
Thank you for your suggestions
I have read the manual, but there is another problem:
As manual said for steady flow in porous media, porosity is not be considered in the momentum equation and the modelling, but why the role of permeability is insignificant in steady flow? (for different viscous resistance pressure contour and volume fraction of fluid are the same)
Well, even in steady state flow, in porous region, Darcy's low is employed (added) in momentum equation to represent surface forces. So, the source term is expressed as follow:

Su=-mu U_avg/K

where K is permeability.
Now, I hope you can see the role of permeability in porous model and steady state condition.
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