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 awacs October 8, 2009 04:35

Questions about convective heat transfer boundary condition

Dear foamers,

I am study the heating process of a solid, which has several heating channels for hot fluid (gas or oil) flowing through. The hot fluid temperature changes little during the entire heating process. So the boundary condition at the channel wall belongs to the classical third-class:

-ks*dT/dn = HTC*(T-T_fluid)

where ks denotes the thermal conductivity of the solid, HTC denotes the heat exchange coefficient between hot fuid and solid depending on the fluid velocity, temperature, and thermal conductivity, etc. , T_fluid is the temperature of the hot fluid, and dT/dn and T are respectively the gradient and the value of the solid temperature at the boundary interface.

Is there a lib in OpenFOAM that performs or nearly performs this BC?

Can anyone help me?

Best regards
Jitao

 awacs October 9, 2009 03:43

I am trying to develop a new convectiveHeatTransfer b.c. under the guidance of

http://www.cfd-online.com/cgi-bin/Op...6301#POST16301
and
http://www.cfd-online.com/Forums/ope...condition.html .

If there is any progress, I will give you feedback as soon as possible.

Regards,
Jitao

 wilko October 12, 2009 20:41

Convective Heat Transfer Boundary

Here is an attempt of an updateCoeffs() function for the convective Heat Transfer BC. The function seems to work properly on some first tests.

void Foam::convectiveHeatTransferFvPatchScalarField::up dateCoeffs()
{
if (updated())
{
return;
}

const scalarField& Kw =
patch().lookupPatchField<volScalarField, scalar>(KName_);

const fvPatchScalarField& Tw = *this;

operator==((HTC_/(patch().deltaCoeffs()*Kw)*Tref_+Tw.patchInternalF ield())/((HTC_/patch().deltaCoeffs()/Kw)+scalar(1)));

fixedValueFvPatchScalarField::updateCoeffs();
}

But I am still in a struggle with some warnings concerning the new variables Tref and HTC. Additionally I am not sure how to change the functions autoMap() and rmap().
Maybe someone can give me a hint.

Good night

Wilko

 awacs October 15, 2009 03:16

Dear Wilko,

Thanks for your reply. From which did you derive the convective Heat Transfer BC? Would you mind sharing the code? I am very glad to test this new BC.