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AleDR January 13, 2011 13:17

foamMeshToFluent : Error for 2D-axi simulation
Hi Forum!

I'm trying to have a benchmark between OpenFOAM and FLUENT with a very simple burner. It is basically constituted by a circular gas inlet and an annular air inlet which end up in a cylindrical combustion chamber.
So my problem is essentially 2D axisymmetric.

In order to have the same mesh for OF and FLUENT runs I created the (3D) grid using blockMesh and wedge shaped blocks.

First I simulate my burner using reactingFoam and then I exported my 3D grid in .msh format and verified it in FLUENT.

Reading this thread I found out that I could obtain a 2D-axisymmetric mesh from my 3D one simply importing it into GAMBIT, deleting the volume and all unnecessary surfaces and then re-exporting it in .msh format... but it doesn't work! :confused:

FLUENT can read the file, but GAMBIT doesn't.

That seems quite strange...
Do anyone know how to manage this?
Here's my .msh file.


[P.S.: it would be nice if fluentMeshToFoam could handle axisymmetric meshes from 2D grids..!]

mvoss January 14, 2011 05:27

try this one:
-make 2.5D Case by extruding in the z-dir.
-make sure the "symm"-faces are in x-y-plane
-make sure every possible node has got a pos. location in x and y
-group the front and back face e.g. "FLUID"
-name the axis faces e.g. "AXIS"

fluent3DMeshToFOAM -*.msh
makeAxialMesh -axis AXIS -wedge FLUID
collapseEdge 1e-6 180

extract the boundary.gz in ~/2/polyMesh
copy everything from 2/polyMesh to constant/polyMesh
delete 1/ and 2/



P.S.: i wrote myself a small script for handling all of this stuff for a multiregioncase... if somebody needs it drop a mail

AleDR January 17, 2011 04:29

Thank you, neewbie! ;)

This is how I can manage to export my high-quality 2D axisymmetric mesh constructed in GAMBIT in OpenFOAM! Very useful script, I'll drop you a email right now!!! :p

Anyway just for this case my problem is the exact opposite: I have a mesh made up using blockMesh (so it is essentially 3D... or 2.5D as you say!) and now I'd like to transform it in a 2D mesh for FLUENT! Si ti possible??

...Anyway I have to say yours is the best option for mantaining the same node position (mesh invariance) to simulate the same case in FLUENT and OF!!

mvoss January 17, 2011 04:43


Originally Posted by AleDR (Post 290686)
I have a mesh made up using blockMesh (so it is essentially 3D... or 2.5D as you say!) and now I'd like to transform it in a 2D mesh for FLUENT!

not quiet but shure did you tried foamMeshToFluent? and i think oyu can cut of the z-Dir. with flattenMesh. never did this.

AleDR January 17, 2011 04:57

Yes, I tried foamMeshToFluent and now I have a .msh file which I can read and visualize in FLUENT but I can't import in GAMBIT for modifying it as a 2D..!

Mmmh, no, I didn't try flattenMesh... but as far as I know it is useful for flattening the front and back boundaries of a 2D mesh, is it?? :confused:

mvoss January 17, 2011 05:02

sorry,... no idea about gambit. Canīt you go for symmetry in FLUENT, .... i know this isn't solving the problem.

AleDR January 17, 2011 06:42

...Mmmh, no, there are not such mesh manipulation features in FLUENT...
Ok, last scenario: I'll create a quasi-similar mesh in 2D using GAMBIT!

But for other cases I will use your suggestions and script:
- make the mesh in GAMBIT as 2D;
- export it in OpenFOAM making it 2.5-D;
- modifying for 2D-axysimmetric simulation.

Thank you!!! :)

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