[bibin.sme]

Hi All,

Is it possible use chtMultiRegionFoam problem for porous media flow??. if so, how to specify interface boundary condition for U, p_rgh etc in porous media??.

Presently I created a case file having 3regions with one region assuming to be porous. In region properties I choose porous as a fluid region then I added fvOptions to add porous region properties. Case file is running perfectly but from the results I see that this resistance is not added. could you please tell me why this is not taking??


Regards,
Bibin

[bibin.sme]

Dear all,

I have a case where one region is a porous region and the other is a clear fluid region. The problem i'm facing is the interface boundary conditions . The interface has to satisfy boundary conditions for U, shear stress, T, and heat flux. How do I create these boundary conditions as coupled BC's or is there any other way to get rid of this issue??

please help me....

Regards,
Bibin

[wyldckat]

Quick answer: Although I'm really late here, the solution is simple enough: porous region cannot be a separate region, it must be part of the complete fluid region that is connected to the porous region.

Edit: See the tutorial case "heatTransfer/chtMultiRegionSimpleFoam/heatExchanger"

[bibin.sme]

Hi Bruno,

The Problem I'm trying to solve is heat pipe using chtMultiRegionFoam. This Problem is having 3 regions (wall, wick & vapour core). The major difficulty I'm facing is the interface b/w the wick & vapour region as its an interface of two fluid regions with phase change.

Can u please suggest some solution to this problem.

Regards,
Bibin

[wyldckat]

Hi Bibin,

Phase change is a whole other type of solver... unfortunately the solvers chtMultiRegionFoam and chtMultiRegionSimpleFoam cannot handle phase change. I'm not familiar with anyone having made public a modified solver of these two that can handle phase changes as well.

What is more important to simulate for your problem:

1. Does the wall have to be physically modeled? For example, do you need to see the changes in temperature along the wall sections?
2. Does the wick need to be physically modeled? Or is the outside surface of the wick really important?

Because if you only want a liquid changing phase to a vapour, after being in contact with a hot medium or hot surface, then there are already solvers for that... if I can remember which ones it is... mmmm... a bit of Googling and I only found a couple of threads relevant to this topic:

• There is this one: New solver for two-phase flows with phase-change heat transfer - although I'm not familiar with it...
• Then there is this thread: Multiphase flow and Phase change due to heat transferevaporation

Best regards,
Bruno

[bibin.sme]

Thanks Bruno,


Let me try the links what you send first.

Regards,
Bibin

[ancolli]

Originally Posted by wyldckat

Quick answer: Although I'm really late here, the solution is simple enough: porous region cannot be a separate region, it must be part of the complete fluid region that is connected to the porous region.

Edit: See the tutorial case "heatTransfer/chtMultiRegionSimpleFoam/heatExchanger"

Dear Bruno,
Why a porous region can not be a separate region?. If you consider a solid porous and a fluid passing trought it. You need to solve different equations for each one and heat transfer between them. Am I missing something?

Regards

[wyldckat]

Originally Posted by ancolli

Why a porous region can not be a separate region?. If you consider a solid porous and a fluid passing trought it. You need to solve different equations for each one and heat transfer between them. Am I missing something?

Quick answer: Study the tutorial case "heatTransfer/chtMultiRegionFoam/heatExchanger" in OpenFOAM 6 or "heatTransfer/chtMultiRegionSimpleFoam/heatExchanger" in OF 5 and older.
I haven't studied this tutorial case myself and the porous part is indeed in a separate region.


However, even if your porous region is made of a solid fabric/material, the problem is that you still need fluid crossing it. This means that you need the non-porous fluid region to transfer fluid back and forth through the porous region. And if not done correctly, you get two separate regions that do not exchange fluid, only heat.

[Madeinspace]

Hi Bruno,


I need to set up a condition on the interface (using internal patch or somehow) but I couldn't figure out how is this possible. Could you please advise.



I need a source term for my momentum equation which is obtained by solving the the Maxwell's equation for elctric potential. The BC needed to solve this equation {as shown} should satisfy on top of metal surface. If there was only metal phase, I wouldnot have problem to set up this BC. But now I have metal phase & Gas phase (interfoam based two-phase solver) and I can't apply this condition on the top surface (of gas) anymore. How do I apply this condition on the interface boundary? I only need to solve for this equation once outside the time loop. The generated source term for momentum equation after solving this equation will remain constant for simplicity.


I have attached a graphics of the domain for easier understanding.



Thanks!