[styx]

I want to simulate the heat transfer between a hot solid sphere and an airflow in a zylinder. I want to simulate the case with chtMultiRegionSimpleFoam. For the beginning is set the turbulence model to laminar.
After a few iterations, I get the following error:

--> FOAM FATAL ERROR:
Continuity error cannot be removed by adjusting the outflow.
Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.
Total flux : 0.003735908
Specified mass inflow : 0.05406901
Specified mass outflow : 0
Adjustable mass outflow : 0


From function adjustPhi(surfaceScalarField& phi, const volVectorField& U,const volScalarField& p
in file cfdTools/general/adjustPhi/adjustPhi.C at line 118.

FOAM exiting


Iam not sure how I should set the boundary conditions. Can anyone help me with this? The case files can be downloaded. I had to delete the mesh information because it was to big.

[zhengzh5]

Originally Posted by styx

I want to simulate the heat transfer between a hot solid sphere and an airflow in a zylinder. I want to simulate the case with chtMultiRegionSimpleFoam. For the beginning is set the turbulence model to laminar.
After a few iterations, I get the following error:

--> FOAM FATAL ERROR:
Continuity error cannot be removed by adjusting the outflow.
Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.
Total flux : 0.003735908
Specified mass inflow : 0.05406901
Specified mass outflow : 0
Adjustable mass outflow : 0


From function adjustPhi(surfaceScalarField& phi, const volVectorField& U,const volScalarField& p
in file cfdTools/general/adjustPhi/adjustPhi.C at line 118.

FOAM exiting


Iam not sure how I should set the boundary conditions. Can anyone help me with this? The case files can be downloaded. I had to delete the mesh information because it was to big.

hey, I had a quick look, and here are my observations:
1. in your sphere/T, you have symmetry plane all over the places...and I think you meant to put zeroGradient? You should double check that.

2. for fluid/U, at the outlet, try putting it as zeroGradient instead of the inletOutlet.

3. I didn't check other fields in the 0 directory, but you should go through them and get rid of all occurrence of "symmetryPlane" for BCs that are actually not a symmetry plane....

Try these and let's see what happens.

Good luck!

[styx]

thank you very much for your answer.

I put the outlet boundary in fluid/U as zeroGradient. Seems to work quite well.

I used snappyHexMesh to create the mesh. Therefore I many boundaries with zero faces. I set these boundaries as symmetryPlane because I saw the same in the tutorial iglooWithFridges. Should I set these boundaries to "empty"?

[styx]

I have another question concerning the boundary conditions.
At the beginning the sphere should have a temperature e.g. of 400K. It should heat up the airflow around it, which has e.g. 300K at the inlet.
But the sphere must have the ability to cool down. I want to simulate the case with chtMultiRegionSimpleFoam.
Which boundary conditions can I use to get this?

At the moment I have the following boundary conditions between the sphere and the fluid:

in 0/fluid/T:
fluidToSphere
{
type compressible::turbulentTemperatureCoupledBaffleMix ed;
value uniform 300;
neighbourFieldName T;
kappa fluidThermo;
kappaName none;
}

in 0/sphere/T:
sphereToFluid
{
type compressible::turbulentTemperatureCoupledBaffleMix ed;
value uniform 400;
neighbourFieldName T;
kappa solidThermo;
kappaName none;
}

Does anyone have a suggestion?