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Lionel S. December 1, 2007 17:18

STL shape into Fluent
Hi all,

I have a problem about CFD and CAD files. I have some STL files which reprensents a shape, and I would like to export it for a CFD software (Fluent by preference) in order to make an aerodynamic study of the shape.

Now, using CAD softwares like Catia or SolidWorks, I can save the files as a STEP or IGS file which is readable with Gambit.

The problem is that the shape is only a "skin" of the 3D shape. I mean that it just represent the surface of the body, and has no thickness (in fact the STL files are resulting of a 3D scanning of a real 3D solid). So exporting it as a STEP or IGS file makes a kind of empty file as a result.

Did already someone encounter such a problem ? Did someone ever scan a real 3D body in order to put in into Fluent ?

Thanks a lot ! Bye


pulgarcito December 3, 2007 08:05

Re: STL shape into Fluent
Hi Lionel,

Try to create a solid volume using STL object in Catia or solidworks, and then export it into gambit.

Another possibilibty is export surfaces as a STEP ( from catia to gambit in my experience this works fine) or IGES object and assemble them into GAMBIT.

Lionel S. December 3, 2007 14:11

Re: STL shape into Fluent
Hi pulgarcito,

"Try to create a solid volume using STL" Yes, but how ? I need to convert a very complex surface into volume. I don't know how to proceed.

"export surfaces as a STEP [...] and assemble them into GAMBIT." The problem is that if I export the surface as a STEP, the resulting file is nearly empty. It seems that the STEP format doesn't support surface. Or I did something wrong...

Mayur December 4, 2007 02:28

Re: STL shape into Fluent
u r right.. I feel u should concentrate on converting surface to volume before exporting somehow... or u may ask fluent people to give u an option to convert from STL->GAmbit.. I feel there is something like this which I looked at long back but not now.

Mayur December 5, 2007 10:37

Re: STL shape into Fluent
GAMBIT has an option to import STL files. GO to Import-> mesh-> STL.

Lionel S. December 5, 2007 15:19

Re: STL shape into Fluent
I didn't know, I will try, thanks

Zhihua December 11, 2007 12:43

Re: STL shape into Fluent
Hi, I use Starcd for simulation and use proam for mesh generation. I draw with proe and always export a STL skin file of the 3D shape. Then it will be imported into Proam to generate mesh inside the shell. I have never used fluent, but I think it should have a similar function.

pulgarcito December 12, 2007 11:41

Re: STL shape into Fluent
Hi Lionel,

I am not sure about the "translation" software you are using. As I said before, STEP format that CATIA v5 writes, works fine in gambit.

Another possibility is to translate STL object in AUTOCAD to ACIS (sat format) and then import it into GAMBIT. It must to work too.

If you want to use fluent as the CFD solver it is better to work in GAMBIT a bit. Sorry for my english

Good luck.

pulgarcito December 12, 2007 11:58

Re: STL shape into Fluent
Hi If the IGES or STEP format it is written in a proper way, they work for vertex, lines, surfaces and volumes.

But for example, in AUTOCAD, if you try to export STL, it is expecting for a body (volume).

Please let me know the software you are using.


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