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-   -   How to implement convection boundary condition (http://www.cfd-online.com/Forums/openfoam-solving/58166-how-implement-convection-boundary-condition.html)

 hsieh January 1, 2009 09:08

Dear FOAMers: Happy New Yea

Dear FOAMers:

Happy New Year!

I would like to implement a new BC at the wall (no solid elements) of a fluid domain.

I would like to read in convection coefficient (h) and free stream temperature (Tinf), then

h(Twall - Tinf) = - K (DT/Dn)

Currently, I am thinking using

gradient() = -h/K (Twall - Tinf) here Twall is explicit.

Is this reasonable? Or, is there a better way to do this?

Thanks!

Pei

 isabel June 30, 2010 03:22

Hello hsieh,

Did you get to implement a convective boundary contidion? I need to implement it too and maybe you found information about that.

 herbert June 30, 2010 04:45

Hi Isabel,

it can be also done implicit, when the conductivty k is present as a field in the solver. You can take a look at the wallHeatTransfer-BC defined in thermophysicalModels/basic/derivedFvPatchFields.

Regards,
Stefan

 isabel June 30, 2010 05:57

Hello Stefan,

I have implemented the boundary condition al follows:

boundaryField
{
ABAJO
{
type wallHeatTransfer;
T_inf 300;
h 5;
}

but when I execute the solver I have the following error:

Cannot find 'value' entry on patch ABAJO of field T in file "/home/isabel/OpenFOAM/isabel-1.5/tutorials/zz/0/T"
which is required to set the values of the generic patch field.
(Actual type wallHeatTransfer)

Please add the 'value' entry to the write function of the user-defined boundary-condition
or link the boundary-condition into libfoamUtil.so

file: /home/isabel/OpenFOAM/isabel-1.5/tutorials/zz/0/T::ABAJO from line 20030 to line 20032.

From function genericFvPatchField<Type>::genericFvPatchField(con st fvPatch&, const Field<Type>&, const dictionary&)
in file fields/fvPatchFields/basic/generic/genericFvPatchField.C at line 7

 herbert June 30, 2010 06:36

Dear Isabel,

I fear you misunderstood me. The wallHeatTransfer-BC itself can only be used together with the basic thermophysical models. I just wanted to show you a guideline how to implement a convective boundary. But you might have to do some changes to make it run with your solver.

Regards,
Stefan

 nimasam December 31, 2010 12:00

hi isabel
could you implement the conductive heat transfer boundary condition finally?

 isabel January 4, 2011 07:49

Hello nima,

Sorry but unfortunately I was not able to implement the convection boundary condition.

 aerothermal January 10, 2012 08:48

did you try to include?

boundaryField
{
ABAJO
{
type wallHeatTransfer;
T_inf 300;
h 5;
value 300;
}
}

The solver needs an initial value for time=0

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