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-   -   rhoSimpleFoam pipe flow crashing (http://www.cfd-online.com/Forums/openfoam-solving/118992-rhosimplefoam-pipe-flow-crashing.html)

showmsj June 7, 2013 15:46

rhoSimpleFoam pipe flow crashing
 
1 Attachment(s)
I have a simple pipe flow model that works fine in fluent but crashes OpenFOAM. The model is attached.
Here are the commands to run the case in OpenFoam 2.1.1:
blockMesh
surfaceFeatureExtract -includedAngle 150 ./constant/triSurface/surface.stl surface.eMesh
snappyHexMesh -overwrite
transformPoints -scale "(.001 .001 .001)"
renumberMesh -overwrite
rhoSimpleFoam
The model runs to about 200 iterations, crashes and the output fields are clearly not headed in the right direction.

I've tried the following:
- first order
- potentialFoam
- a variety of setting changes suggested on the forums :)
Any help would be appreciated.
Thanks,
Sam

VSass June 8, 2013 17:43

Sam,

i've checked only your controlDict file, because i had the same problem when i used rhoSimpleFoam. First of all, i suggest you lower your timestep, even put a constrain of max Courant 0.5 or 1. I strongly believe this could fix your problem, since your BCs are sufficient.

I wait for your results.

showmsj June 19, 2013 10:16

Solved
 
I reduced the rho relaxation factor to 0.05 and ran the model in 2.2. The results now look correct.

-Sam

showmsj July 1, 2013 15:37

Incorrect transport properties for air
 
1 Attachment(s)
The transport properties should have been:

transport
{
As 1.458e-06; // C1 Coefficient
Ts 110.4; // C2 Coefficient
}

That change plus the relaxation change brings the result within 30% of the fluent and test results. This is still not close enough in my opinion...

I have attched a new version of the analysis. Again the commands to reproduce are:

blockMesh
surfaceFeatureExtract -includedAngle 150 ./constant/triSurface/surface.stl surface.eMesh
snappyHexMesh -overwrite
transformPoints -scale "(.001 .001 .001)"
renumberMesh -overwrite
rhoSimpleFoam


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