[ep4]

Imposing a heat flux on a surface is equivalent to impose the normal temperature gradient. (q=dT/dn)

Example:

wall{
type fixedGradient;
gradient 2;
}

[braennstroem]

Hi,

there is a bc on the wiki:

http://www.cfd-online.com/OpenFOAM_D...ges/1/815.html

Fabian

Hello Eric,
-> FOAM Warning :
From function Field<type>::Field(const word& keyword, const dictionary& dict, const label s)
in file /home/rkahraman/OpenFOAM/OpenFOAM-1.5/src/OpenFOAM/lnInclude/Field.C at line 252
Reading "/home/rkahraman/OpenFOAM/rkahraman-1.5/run/tutorials/my_icoFoam/tube_1/0/T::fix edWalls" from line 25 to line 26
expected keyword 'uniform' or 'nonuniform', assuming deprecated Field format from Foam version 2.0.


keyword outlet is undefined in dictionary "/home/rkahraman/OpenFOAM/rkahraman-1.5/run/tutorials/my_icoFoam/tube_1/0/T::bou ndaryField"

file: /home/rkahraman/OpenFOAM/rkahraman-1.5/run/tutorials/my_icoFoam/tube_1/0/T::boun daryField from line 25 to line 39.

From function dictionary::subDict(const word& keyword) const
in file db/dictionary/dictionary.C at line 271.

FOAM exiting
I have put the BC like your example but it gives me that message...

hi to all

someone could help me to how to use that fixedGradient BC?

Best regards

Emo

[villet]

Emo: Read the error message. You need to add word "uniform" after "gradient" and before the uniform value.

[nandiganavishal]

Hi All,

I am new to Openfoam. I have a case where I need to set B.cs given by the equation

-D1*dC1/dn - K1*C1*dPhi/dn = 0 where n is the normal direction.

I am solving a 2d system hence I want to set the flux in the y direction as zero. i.e
-D1*dC1/dy - K1*C1*dPhi/dy = 0
where C1 and Phi are my variables. I am solving coupled equations.

I hope i will get some response.

Can anyone suggest how exactly I have to go about incorporating this boundary condition.

Kindly do the needful.

Thanks

Regards

Vishal

[thomasduerr]

Hi,

are there any news or hints how to impose a boundary condition of fixed heat flux to walls in OF 1.6?

Thanks!!!!!!!

[vitor.geraldes@ist.utl.pt]

One simple way to implement a mixed/Robin boundary condition consists in adding a source term to the scalar transport equation that is zero everywere, except in the control volumes adjacent do the selected patch. This is not a clean approach, but it works quite well.

[nygbook]

Originally Posted by vitor.geraldes@ist.utl.pt

One simple way to implement a mixed/Robin boundary condition consists in adding a source term to the scalar transport equation that is zero everywere, except in the control volumes adjacent do the selected patch. This is not a clean approach, but it works quite well.

Maybe this is a good idea. But if this is multiphase flow in pipe. How do I add the source to energy equation?

[vitor.geraldes@ist.utl.pt]

The best way to deal with this problem is to use the boundary-condition groovyBC. I have tried it in this type of BC and it works quite well. ( please see http://openfoamwiki.net/index.php/Contrib_groovyBC)

[jorkolino]

Originally Posted by vitor.geraldes@ist.utl.pt

One simple way to implement a mixed/Robin boundary condition consists in adding a source term to the scalar transport equation that is zero everywere, except in the control volumes adjacent do the selected patch. This is not a clean approach, but it works quite well.

How do I identify the control volumes adjacent to a given patch in order to assign source term to them?

[palmerlee]

try something like this:

wall
{
type fixedGradient;
gradient uniform 10;
}

[ben_]

Originally Posted by ccless

I am getting the same effect, any luck on this. It seems to only heat up the cells in the proximity to the walls. Basically, not providing any advection of thermal energy into cells next to the ones on the wall. Any ideas on this one?

Hi, Did you ever get a response for this? I realize this is coming pretty late

[ttsurvase]

Use externalWallHeatFluxTemperature in file T of 0 folder.
<patchName>
{ type externalWallHeatFluxTemperature;
mode coefficient;
Ta constant 300.0;

h constant 10.0;

thicknessLayers (0.1 0.2 0.3 0.4);
kappaLayers (1 2 3 4);

kappaMethod fluidThermo;

value $internalField; }


This is for convective heat transfer.

Conductive heat transfer example is described below
wall
{
type externalWallHeatFluxTemperature;
mode flux;
q uniform 1000;
kappaMethod fluidThermo;
value uniform 300.0;
}
I am using OF-v2006 version.