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August 17, 2015, 11:02 

#21 
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I didn't have time to run my latest case, as I took me around 6 hours to modify the geometry. But, what I am concerned about, is to define the BCs in a way that changing the porosity, affects the velocity field in the surface water. The thing that I could not get, when I changed the internal face to a boundary face . Maybe, in this latest case changing the porosity affects the velocity field, but I don't think that it will be very accurate, because for the first half (before x=7.2 m) it seems that there is no wall (as it is cyclic) and for the second half it is all wall!
If this was the only geometry that I wanted to use, I would implement the idea in my previous post (dividing the porous medium into many parts...), but I want to have simulations with different shapes of the porous medium, so for every case I have to spend around 12 days on making the geometry. That's why I would like to have some BCs that switch between cyclic and wall. 

August 17, 2015, 11:27 

#22 
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My problem is that I have a boundary which is acting as a wall, and at the same time the flow passes through it. Do you think is that possible to define such a BC?
Best regards, Hessam 

August 17, 2015, 11:55 

#23 
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Bruno Santos
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Hi Hessam,
Well, unfortunately I don't have the time needed for implementing a proper boundary condition for this, specially because I don't have enough experience in this kind of advanced boundary condition you're looking for... i.e, it would likely take me several days to do it. Nonetheless, the "groovy6" case you provided gave similar results and after some tests, it seems attached files can get the job done:
Code:
Time = 200 smoothSolver: Solving for Ux, Initial residual = 2.0294e06, Final residual = 2.54496e07, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.000210234, Final residual = 1.55541e05, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.000114592, Final residual = 3.30167e06, No Iterations 4 GAMG: Solving for p, Initial residual = 0.000465951, Final residual = 2.30545e05, No Iterations 1 time step continuity errors : sum local = 1.93143e05, global = 6.60033e06, cumulative = 0.0276762 smoothSolver: Solving for omega, Initial residual = 3.4969e06, Final residual = 3.54347e07, No Iterations 1 smoothSolver: Solving for k, Initial residual = 3.60996e06, Final residual = 8.3163e07, No Iterations 1 ExecutionTime = 911.31 s ClockTime = 955 s My guess is that this is enough for your to proceed with your work. Best regards, Bruno
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August 17, 2015, 12:01 

#24 
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Hello Bruno,
I really appreciate your help! I hope your guess will be right! Thank you Hessam 

January 19, 2016, 01:25 

#25 
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Hello Bruno,
I hope that you are fine. I am still working on the permeable wall in my case. Since I could not find a way for defining an appropriate BC on the permeable wall I divided the porous medium into 23 parts and defined Cyclic and Wall BCs alternatively on each part (just a more precise form of the methodology that you proposed). The results have improved, however I am not satisfied yet! I want to find a way to make the permeable wall as a wall in which there are many holes (depending on the porosity of the materials). I am really impressed by the geometry that I found in paper entitled: "Direct numerical simulations of interface dynamics to link capillary pressure and total surface energy". I am attaching a photo of the geometry to this post. I guess that making such a geometry would be difficult (specifically for me as a beginner). I think since I want to test this geometry, instead of making holes I can replace them with squares. But, anyway I don't know how make such a geometry. Could you tell me what the easiest way is to make a surface which looks the same as the attached figure? Your help would be greatly appreciated. Best regards, Hessam 

January 31, 2016, 10:49 

#26  
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Bruno Santos
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Hi Hessam,
Sorry, these past few weeks have been very busy for me and only today did I finally manage to properly start looking into questions here on the forum. Quote:
OK, so there are 2 details that we need to take into account:
Let me find a tutorial in OpenFOAM that we can use for practice... A quick search: Code:
find $FOAM_TUTORIALS name Allrun  xargs grep createBaffles Attached is the package "damBreakPorousBaffle.tar.gz", for which I used OpenFOAM 3.0.x. To use it:
Best regards, Bruno
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September 16, 2016, 05:28 

#27  
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Quote:
I have a much simpler suggestion, why not use darcy equation for the porous region and the usual Navier Stokes for the other medium? Much like conjheat case, only that instead of coupling the temperature equations, use darcy equation? However, I'm not exactly sure if we'd need to make two separate meshes and then couple them together. Also i have another question, the case described by Majed is much more complicated than mine. I'm not looking to model the porous media for now, only the domain through which the fluid flows. I'm running a desalination case. Its single phase but with dissolved salts. The walls need to be made permeable for water while it rejects the salts. Is there any predefined boundary condition or a tutorial similar to my case? Regards, Gohar Shoukat 

May 22, 2017, 05:03 

#28 
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Stefan
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Hi Foamers,
i'm facing more or less the same problem searching a BC for a permeable wall. I followed your discussion, but i cant figure out what would be the best solution to get rid of this situation Could you archive any sucess until now? Best Regards Stefan 

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