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-   -   Porous media boundary conditions (http://www.cfd-online.com/Forums/fluent/99696-porous-media-boundary-conditions.html)

aggie April 10, 2012 01:53

Porous media boundary conditions
 
Dear all,
I want to simulate a cylindrical vessel in which some part of the cross section is a demister pad with a thickness of 15 cm. I believe the best thing to handle the demister pad is to model it as porous media. Do you agree or disagree?

If you agree, I have a question regarding the boundary conditions of the porous media. I have three volumes following each other, the one at the middle being porous media. What should I do for the boundary conditions of the porous media? For the contact surface of porous-non porous volumes, should I define wall, interior, porous jump, etc. ?

I feel that this is a very basic question, this is the first time I am trying to model porous media and official Fluent tutorials are not helpful. Actually they are never helpful :)

Thanks.

aggie April 10, 2012 05:50

Any ideas??

delaneyluke April 13, 2012 08:05

Not sure what a demister pad is, but here's my view on porous media
1) I generally follow the practice of using a porous media only if i have flow in more than 1 direction through the media (i.e normal flow and one other direction)
2) If your flow is predominantly normal to the media then i would suggest using a porous jump
3) If you know your pressure drop then it's just a matter of calculating the resistance coefficients
4) If you do not know your pressure drop then I would suggest solving the flow through a small sub section of your porous media for 3 or more velocities, plot a regression (quadratic) of velocity v/s pressure drop and use the coefficients as your resistance coeff.

With regards to the interfaces between the porous-non porous volumes, they would have to be interiors or interfaces, if all 3 volumes are fluid volumes.

Hope this helps
Regards
Luke

chemkin June 17, 2012 09:51

I have modelled the same thing.
you need not to worry about the over lying boundary of the porous and non porous media. just bring them as it is in the fluent and the made an interface or interior. each will work


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