[zombiaska]

My friend is an engineer and he has CAD format drawings. Next step is to use those drawings in Ansys Fluent modelling.

He can convert to these formats and I use for reading and meshing Icem CFD 12.0.1:
IGES
STEP
PARASOLID
ACIS

I checked STEP and PARASOLID. I am new at modelling and I couldn't see the difference. Maybe anyone could name what flaws comes up and what problems occur?

As I read forum I understood that the best formats are Parasolid and worst step and iges, but I can't tell the difference.

[PSYMN]

IGES isn't always bad... For a simple model it may look fine. But when people tell me the spend a lot of time repairing geometry, you can guess they are probably using IGES or Step. In other words, some models may be fine, but they leave you with a higher probability of a surface being badly trimmed or something like that. Even when they fail, it is usually only a few surfaces that fail, so the more complex trimmed surfaces you have the more likely you will have a failure.

ACIS and Parasolid are better, but reading the CAD directly (if that is an option for you) is the best.

Also, if you are interested in parametric studies, ACIS or Parasolid keep their entity names which makes scripting possible; IGES scrambles every time. Of course, CAD is the best because you can let Workbench drive the parametric updates directly thru the CAD.

[zombiaska]

Hey PSYMN,

Thanks for very informative answer. It is a lot of useful info
I still don't have CAD file but I am waiting when my friend will send it.
As I know CAD files open when you have workbench, but I only have ICEM CFD. I will give a try, maybe it will be opened.

[PSYMN]

There are Workbench readers and Workbench cad interfaces and ICEM CFD readers and ICEM CFD cad interfaces and for versions of ICEM CFD newer than R13, all of them will work, even with standalone ICEM CFD.

[macfly]

I'm a little disappointed about the CAD export from DesignModeler to Icem CFD within Workbench: entity names are modified in Icem CFD.

Look at the attached example of a simple duct with inlet, outlet and sidewalls. I created surfaces from faces in DM, hoping to find the same surfaces already properly named in Icem CFD later. But that didn't work, I have to create parts and rename everything again in Icem CFD.
https://dl.dropboxusercontent.com/u/...to_IcemCFD.pdf

My university doesn't have the license for parasolid or ACIS import in Icem CFD, but imho the direct link DM=>Icem CFD in Workbench should be flawless (find the exact same thing in DM and Icem CFD). I guess Ansys is working on that issue?

[PSYMN]

I wouldn't say they are scrambled, more like "appended". They added a number (1, 2, 3, or 4) because there are 4 parts. The other number is used for sub bodies... I am sure all that extra stuff would be useful for certain complicated situations.

I have always found it mildly annoying at best.

But I can see your point (it looks silly for a simple case) and I will talk to development about handling simple cases like this differently (so INLET just becomes INLET).