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-   -   Porous medium flow (http://www.cfd-online.com/Forums/openfoam-solving/59447-porous-medium-flow.html)

shailesh August 7, 2007 04:52

Hi, I am trying to simulate p
 
Hi,
I am trying to simulate porous medium flow using rhoPorousSimpleFoam. The geometry is a porous cylinder within another non-porous cylinder with inlet/outlet pipes. The problem I am having is in defining the porous zone required by the solver.

I am using Netgen to define and mesh the geometry. I defined 2 top-level-objects to differentiate between the porous zone and the rest but OF will not read more than 1 domain. I also tried fudging the Netgen mesh file to write everything as a single domain but extracting the element information for the porous zones. But, OF does not like that since a boundary condition is defined on internal edges.

Hope the above makes sense.
I have attached the Netgen geometry and mesh (Neutral format). Is there any obvious fix to this?
I am very new to OpenFoam so please be patient with me:-)
Many thanks in advance.
cheers,Shailesh

shailesh August 7, 2007 05:00

sorry i forgot to attach the f
 
sorry i forgot to attach the files.




shailesh August 7, 2007 05:04

sorry i forgot to attach the f
 
sorry i forgot to attach the files.

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif cylinderpipesporous.geo

olesen August 7, 2007 05:06

The porous media works with a
 
The porous media works with a single region, but needs cellZones. If you can convince Netgen to output a list of cells, you can make a cellZone quite easily.

shailesh August 7, 2007 05:21

Mark, I tried fudging the Net
 
Mark,
I tried fudging the Netgen mesh file to do just this.
I initially meshed the geometry with 2 top-level objects which gave me the the elements to construct the CellZones. I then manually changed the domain nos. to a single domain and tried getting OF to convert it. But the problem then is that the slip BC patch on the inner cylinder surface is part of the internal mesh which I guess OF does not like.
does this make sense???
Shailesh

mkraposhin August 7, 2007 05:57

Here is an answer: 1) define
 
Here is an answer:
1) define surface, which contains porousity volume in Netgen.
2) Mesh this surface and export it in .stl format
3) place .stl file in root of your case directory
4) open .stl file and write name (any symbols) in the first string, save it.
5) use cellSet to produce set of cells, that reliese on surface, (look in cellSetDict)
6) run setsToZones to produce cellZones
7) That's all!
And here is my question to you:
do you understand how to interpetate parameters of porousity:
e1/e2/3
d,f - for Darcy
c1,c2 - for Crosspowerlaw

shailesh August 7, 2007 06:11

thanks Kraposhin. i'll give th
 
thanks Kraposhin. i'll give that a try.
as for the porosity parameters,
e1,e2,and e3 define the anisotropy directions of the porous region.
definitions for d,f,c1,c2 can be found in porousZone.H.
hope this helps.

mkraposhin August 7, 2007 06:20

SORRY FOR BAD ENGLISH! Ok, i
 
SORRY FOR BAD ENGLISH!
Ok, i understand this, but and i know, that d - is a viscous resistance (dzita/l) and f - is inertial resistance. and E.T() = (e1 e2 e3) have some common with permeability tensor. What is a form for simple porous geometry (row of tubes in chess-order)?
It would be nice to share some experience with you

plmauk September 14, 2007 05:18

Hi, anybody. I have to add a
 
Hi, anybody.
I have to add a porous zone to an existing mesh.
The geometry of the mesh is a cylinder.
How can I do that?

The question might be quite stupid, but I'm new in OpenFoam.


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