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How to combine convection and heat flux BC?

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Old   December 21, 2023, 10:06
Default How to combine convection and heat flux BC?
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nicolas Claverie
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Hello,

I want to simulate a solid sphere in open air receiving a constant heat flux.

Basically the BC of my sphere should be a combination of

air_to_sphere

{

type externalWallHeatFluxTemperature;
mode power;
Q uniform 5; // 5 W received on the boundary
kappaMethod solidThermo;
value uniform 300;
}


for the constant heat flux, and

air_to_sphere
{
type compressible::turbulentTemperatureRadCoupledMixed;
Tnbr T;
kappaMethod solidThermo;
value uniform 314;
}


For the convection.

Is there a way to do that?
One option would be to add a constant radiation flux on the sphere but I never used radiation in a model so I am not very confortable to do that.

PS: install information if relevant:
Windows 11 pro 22H2
WSL 2.0.9.0
Ubuntu 22.04.3 LTS
Openfoam 2306
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Old   December 21, 2023, 13:00
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Tobermory will become famous soon enough
You want to specify both the heat flux and the HTC, without any radiation present? Surely this is over-specifying the boundary condition?

And what do you mean by "convection" ... it can't be the usual meaning, i.e. convection to the fluid inside the domain, since you are already specifying the heat flux (which will in turn define the boundary surface temperature) ... and the only way the code could achieve this would be to set both the boundary temperature and the cell temperature, which is not allowed.

If you mean "conduction" through the wall, rather than "convection", i.e. set an external surface temperature and a heat transfer coeff thru the wall, then this is over-constrained & impossible to implement.

So I am a bit puzzled my friend as to what you are trying to achieve. It doesn't sound physical. Ofc, I may have misunderstood ...
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