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Heat source in porous zone

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Old   October 5, 2009, 11:28
Default Heat source in porous zone
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Thomas Wolfanger
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Hello Foamers,

I want to model a flow with a porous zone which works well using rhoPorousSimpleFoam in OF 1.6.x.
In a next step, I want to add a heat sink to the porous medium. Is it a good idea to use (and probably extend) the porousZone machinery to this end or is it a better idea to do something on the solver level?
A possible approach is to modify the hEqn with an appropriate source term and multiply it with a field value which corresponds to 1 in the porous region and 0 elsewhere, but this seems not to be very elegant.
What do you think?

Best regards,
-Thomas
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Old   June 8, 2011, 08:04
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Dima Risch
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hallo Thomas,
i want as well to add a heat source to the porous zone like you, and want to ask how you handle this?

kind regards,
Dima
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Old   June 17, 2011, 03:47
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Dima Risch
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great job guys
looks like what i am looking for is implemented in OF 2.0.0

best regards, Dima
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Old   June 17, 2011, 09:43
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Gian Maria Di Stefano
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What theory model are you using?

I have the same problem, but I have resolved it applying a modify to hentalpy equation, changing the laplacian therm
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Old   June 17, 2011, 10:15
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Dima Risch
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at the moment i am using just test models, like pitzDaily or a simple inlet outlet channel (tube) with a pZone in it

i was going to resolve it by applying a modify to hEqn as well, changing the source term -> not finished at the moment, just at the beginning

in the new version of OpenFoam there is a thermalPorousZone model (fixedTemperature)

in my further work i will try to add a new model something like fixedEnthaly
but my knowledge of the OF source structure is low at the moment, so i hope there is not a lot of change to do
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Old   June 22, 2011, 04:56
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Hi Dima,

Did you succeed in using the fixedTemperature model for thermalPorousZone ?

When I try it on the rhoPorousMRFSimpleFoam tutorial, it gives me strange behaviour with T (near 0 after the thermal porousZone) and with rho (limited at 1.5 by fvSolution also after the porousZone).

I get this behaviour with different values for the temperature coefficient (even 0).

Could you tell me if you experienced this model ?

Best regards,
Fabien
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Old   June 22, 2011, 07:01
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Dima Risch
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Hi Fabien,

i didn't succeed in using the angledDuct case too, the same problems occur

so something might be wrong to the calculation (hDiag and hSource) in fixedTemperature.C
or the (rho) settings in the fvSolution ...

but i am not familiar with that at the moment

regards, Dima
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Old   June 30, 2011, 08:35
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Dima Risch
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hello,

i changed the fixedTemperature.C

...
forAll(zones, zoneI)
{
const labelList& cells = mesh.cellZones()[zones[zoneI]];

forAll(cells, i)
{
hDiag[cells[i]] += 1/rate*V[cells[i]]*rho[cells[i]];

hSource[cells[i]] += V[cells[i]]*rho[cells[i]]*T_;

}
}

it looks much better now, but not correct at all
would be nice if someone who knows how to handle this could reply

regards, Dima
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Old   January 26, 2012, 08:26
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Andrea Pasquali
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Hi Dima,
I'm workin on thermal porous media too.
I checked the OF 2.1 and the fixedTemperature eqn. source is fixed with Cp:

Quote:
...
tmp<volScalarField> Cp = thermo.Cp();
// TODO: generalize for non-fixedTemperature methods
const scalar rate = 1e6;
forAll(zones, zoneI)
{
const labelList& cells = mesh.cellZones()[zones[zoneI]];
forAll(cells, i)
{
hDiag[cells[i]] += rate*V[cells[i]]*rho[cells[i]];
hSource[cells[i]] += 00098 rate*V[cells[i]]*rho[cells[i]]*Cp()[cells[i]]*T_;
}
}
...
I did not check if is correct yet...
I'm trying also to implement non-fixedT, maybe a powerLaw, but I don't know which kind of law I can use.
Do you know something about it?
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Old   May 4, 2012, 05:38
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Hi Andrea,

Did you manage to implement a non-fixedT law in the thermalPorousZone ?

If yes, would you mind sharing it with me ?

I tried by myself but I'm stuck with hDiag and hSource, I don't unserstand how it works with hEqn.

No matter what I try, I got weird results in the temperature field (mostly very low or very high T field).

Thanks,
Fabien
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Old   May 4, 2012, 15:59
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Andrea Pasquali
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Hi Fabien,
no I did not implement it... what law did you use for it?
I'm also interesting to add different thermal conductivity (kappa field) just inside the porous medium.
I'm thinking at: kappa_eff = porosity*kappa_porous_medium + (1-porosity)*kappa_fluid.
Do you know something about this?

Thanks

Andrea
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Old   December 16, 2013, 10:49
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nadine moussa
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Hello Andrea,

did you managed to calculate an effective conductivity as function of the porosity?

I am so intrested in this subject!

thanks a lot,
Nadine
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