CFD Online Discussion Forums - [CAD formats] Problem exporting a STL-file from ProE

Hello Community,

I am quite new to OpenFoam. I have done some tutorials and simple Simulations on my own so far and had no problems.

But now I would like to use a CAD-geometry which I have in a PRT-format (ProE) for a simple inflow simulation. My Problem is that I am not able to export a STL-File with all the patches I would like to define, e.g. inlet, outlet and wall. For the meshing I would like to use snappyHexMesh, because I am going to simulate in OpenFoam and the mesh should have a boundary layer and several refinement zones.

So far I have found three ways using different tools to export the STL.

1. Exporting the whole geometry as a .STL-File from ProE and defining the patches by editing the STL (saved in ASCII-Format) in an editor. This is a simple and easy way as long as your CAD-geometry stays simple and you have nearly unlimited time to spend. But when it comes down to editing my case, I only see numbers and some words in a big STL and it is really exhausting to find all the faces of a patch. So this way seems to be useless or lets better say ineffective for me.
2. The other way is to export several STEP files from ProE (for all the different patches and all with the same reference coordinate system) and then importing them into FreeCAD. There I managed to export them as a STL. The problem in this case is, that the quality of the STL is not satisfying enough for sHM. Shortly saying there are holes in it. And if you try to close all the holes you get illegal faces. And I really tried out many things to improve the quality… but still nothing ...
3. The last way is at the moment also a dead end. Like in the second case I got a STEP out of ProE but in this case only one File is necessary. Then I use NETGEN to create a Mesh and to define my patches. This is really easy in NETGEN. And because everything seems to be perfect and easygoing, I exported the STL out of NETGEN. In my credulity I thought there will be my defined patches in the STL. But looking in it I was bitterly surprised, there are no patches only a single one including all the faces….
So still I have got nothing...
Here is a list of programs I can use (this is bit of a problem in my company … I can only use them. Others need an approval and this is a story which could be even longer then defining the patches manually in an editor…)

· ProE
· Editor/Notpad
· OpenFoam 2.3.1
· NETGEN
· FreeCAD

I think it can't so difficult but I do not the right and effective way to find all my patches...

Could somebody help me by telling me another way of creating a STL. I also appreciate if someone can correct the mistakes I possibly have made.

Thank you in advance.

Greetings

Michael :)