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-   -   OpenFoam vs Fluent (http://www.cfd-online.com/Forums/openfoam/84376-openfoam-vs-fluent.html)

Akuji January 27, 2011 09:07

OpenFoam vs Fluent
 
I try to calculate a flow around building. So, I did a mesh in gambit and calculate in Fluent. After this, I load mesh in OpenFoam and try to calculate in it. I use the same boundary condition, but every time i have very big value of time step continuity error, epsilon and k.
I use a k-epsilon model in SimpleFoam.
Why Fluent calculate my problem, and OpenFoam can't?

cheng1988sjtu January 27, 2011 10:58

Is it a 2D model?

Can you use checkMesh in OpenFoam to see the detail of the mesh?

Maybe you've got some undefined faces...

Akuji January 27, 2011 11:01

Quote:

Originally Posted by cheng1988sjtu (Post 292480)
Is it a 2D model?

Can you use checkMesh in OpenFoam to see the detail of the mesh?

Maybe you've got some undefined faces...

My Mesh is 3D. I always use checkMesh after import it from another application. Mesh is OK

mvoss January 28, 2011 04:47

please check for the internal fields in ~/0/epsilon,k,u and of cource for the bc.values (garbage in , garbage out... )

i think you just started with unphysical internal values. no offense, but as often is i blew up a solver run as often it was my fault because of bad initialization and fancy bc.

try to do a potentialFoam on beforehand to get an initial guess.

neewbie

amgode January 28, 2011 04:51

Could you please elaborate a little more on your problem.....with regards to the schemes you used in OpenFoam and also the solvers used...



Regards,

Amol

Akuji January 31, 2011 09:15

today I try to use a Spalar-Allmaras model, because k-eps was converged only with vary small relaxation factors.

When I look velocity, I see, that in magnitude I have only positive values, in axes y and z-positive and negative. But in X-only positive, so as I understand I haven't a vortex.
But fluent shows a lot of vortexes.

Where mistake?

alberto February 1, 2011 02:30

Hello,

before we can try to answer you should give us a bit more information :-)

- What solver are you using?
- Post your fvSchemes and your fvSolution dictionaries
- Post the output of checkMesh
- Describe the setup of your boundary conditions

Typically if you are forced to use very small relaxation factors, it means there is something wrong in the case setup (I would say most probably BC's).

Best,

Akuji February 2, 2011 08:39

4 Attachment(s)
Hello,

I use case simpleFoam
My fvSchemes and fvSolution

Also, output of checkMesh-in log file

And boundary Conditions are in 0.zip


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