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Using outlet value as inlet

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Old   October 13, 2021, 06:20
Default Using outlet value as inlet
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Humam
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Hello, I am new to OpenFOAM and I'm trying to simulate a simple closed loop heat exchanger system with pseudo pump inside using the buoyant solver. Previously I used buoyantSimpleFoam for the closed loop analysis with zero initial velocity. I have looked around and figured out that I need to break the loop and then insert an inlet patch with a velocity value (and I think I will have to use buoyantPimpleFoam for this?).

Now I need to find a way to use the temperature value (and possibly velocity too) from the outlet patch as value for the inlet patch to retain the model of a closed loop system. I found this thread (Inlet temperature = outlet temperature + offset?) but they used groovyBC and I couldn't find one that's compatible with OF8. How should I approach this?

Thank you for taking your time reading this question
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Old   October 18, 2021, 14:25
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Hi Humam,
Don't break the loop and you don't need groovy bcs. If I understood the problem correctly, you need to do this:
Keep the closed loop and create cellZone containing the cells which has to represent the pump. The apply the fvOptions ( fvModels as for OF9) entry meanVelocityForce on this cellZone using the desired velocity vector. There is some tutorials about meanVelocityForce in the official OF tutorials.
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Hussam
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Old   October 19, 2021, 00:10
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Quote:
Originally Posted by tobiasS View Post
Hi Humam,
Don't break the loop and you don't need groovy bcs. If I understood the problem correctly, you need to do this:
Keep the closed loop and create cellZone containing the cells which has to represent the pump. The apply the fvOptions ( fvModels as for OF9) entry meanVelocityForce on this cellZone using the desired velocity vector. There is some tutorials about meanVelocityForce in the official OF tutorials.
Regards
Hussam
Hello Hussam, thank you for replying to my question.

I didn't know that I don't have to break the loop and I'm glad there was an easier way to do this! I followed your advice and it works exactly as I hoped it to be. Thank you very much, I'll come again if I encounter any problems.

Regards,
Humam
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Old   October 28, 2021, 05:14
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For anyone in the future who finds this thread: there is also an easy way to use an outlet value for an inlet

There's a patch type called outletMappedUniformInlet
You set the outlet patch as normal to zeroGradient or similar, then set the inlet patch to
Code:
<inletPatch>
    {
        type            outletMappedUniformInlet;
        outletPatchName aPatch;
        phi             phi;
        value           uniform 0;
    }
The inlet patch will find the patch named aPatch, calculate the average value, and set the inlet patch's value to that average everywhere
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closed loop, heat exchanger, inlet bc temperature, loop.

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