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

Hello hsieh,

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

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

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

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

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

Hello nima,

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

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