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Boundary conditions for two connected fluid region.

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Old   October 21, 2010, 16:29
Default Boundary conditions for two connected fluid region.
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Anh Le
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I want to creat two different fluid regions with different meshes. The outlet of region 1 will connect to the inlet of region 2. Assuming the flow goes through the inlet of region 1 to outlet of region 2.
Then, the BCs for U and P should be:
-Region 1, inlet: U fixed value, P zeroGradient
- Region 2, outlet: U zeroGradient, P fixed value (0 - ambient pressure)

So, what should BCs for U and P at: Outlet of Region 1 and Inlet of Region 2 (actually, they coincide but in different meshes).

The BC patches of Outlet, region 1 and Inlet, region2 should be "regionCouple" ???
Many thanks for helping me out of this.
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Old   December 4, 2012, 06:23
Default defining internal boundary conditions
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version: OF-2.1.0
geometry: containing a number of fluid regions surrounded by solid regions. Its like a 2D rectangle with solid walls having inlet/outlet fluid regions and internal fluid regions.
problem: coupling solid/fluid regions in the same way as defined in tutorial but how to couple fluid/fluid regions (right now i am using zeroGradient for U,T, p) and solid/solid regions.

And as I use to run the simulation, after some iterations temperature goes to very high values.

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Old   December 5, 2012, 00:07
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Hey Jamal and Anh,

have a look at

Linse, ZKW and me are working on the same issue.
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Old   June 20, 2019, 16:45
Default Two touching fluids for heat transfer in OpenFOAM
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Hi there,

Sorry for reactivating this dormant thread. I have a very basic question! I know that in many CFD software two fluids should be separated by a solid unless they form a mixture (i.e. VOF). This is not the case in my simulation.

I want to simulate heat transfer using chtMultiRegionSimpleFoam between two fluids. The geometry is similar to a double pipe heat exchanger. Since OpenFOAM is inherently different from many other solvers, I was thinking whether it is possible to couple the two fluids directly (without simulating the sandwiched solid between them). If yes, what should be assigned in the shared boundaries?

I tried some cases but am getting divergence after few iterations (negative temperature)

Thanks a million in advance...
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