[Svetlana]

Hello! I have around 10 million mesh elements. The CFX-Pre window takes over 10-20 minutes to open. What's worse, it appears to be using only one CPU core out of 8 (Windows) or 16 (Linux). 16GB RAM (Windows) or 96GB RAM (Linux) available. The .cfx file size being only 3GB. What could possibly take it so long? Any tips? Thanks!

[ghorrocks]

CFX-Pre does take a very long time to load some times. It is only a single threaded application so it will only ever run on a single CPU. So you cannot fix that.

But here are some things to do to speed CFX-Pre up:
1) Run it stand-alone, not in workbench. You get a lot more control over things stand-alone.
2) Before you load your file, turn off some options (under Edit/Options) which can take forever:
a) CFX-Pre/General/Auto Generation - turn off auto default interfaces
b) CFX-Pre/Graphics Style - Object highlighting - change to bounding box.
c) CFX-Pre/Render - Turn off Draw Faces and Specular lighting. Note you won't see anything if you do this! If you are really desperate you can turn visibility off. You won't see anything, but for some really big models it is required
d) CFX-Pre/Labels and Markers/Labels - turn Show Labels off.
e) CFX-Pre/Labels and Markers/Boundary Markers - turn Show Boundary Markers off.

You might have to close and reopen CFX-Pre to make these options take effect.

But try loading your file then and hopefully it will be much faster. But it will not look as pretty, that is the price you pay.

[Opaque]

Which version are you running?

What operating system are you using? Windows 10? Linux?

Sometimes is not only about the mesh, but the physics details, say 100's of domains, domain interfaces, boundaries, etc.

[ghorrocks]

Opaque's comments remind me - a common source of this problem is geometries with thousands of surfaces. ANSYS meshing by default creates an individual surface on each one, and that can overwhelm CFX-Pre. If you generate your mesh in ANSYS Meshing, then load it into ICEM (or any other good mesh editor) and merge all the surface groups you do not need into one big surface group. Then import the ICEM mesh into CFX-Pre and you should only have the surface groups you need, and CFX-Pre will run much better.

[Gert-Jan]

The fact that your .cfx file is 3Gb, while you have only 10 million elements, tells me something is wrong, or at least different from standard. With 10million elements, I usually end up with a file size of around 100 Mb.

So I guess, Glenn is right, the geo might be too complex with too many named surfaces.

[Svetlana]

Thank you! 2a helped the most.

[Svetlana]

It's 2021R1, problem with in Linux and Windows. Agreed that there is too many faces named F3445.435 etc in CFX-Pre. Would be very interested to know a few short tips about how to merge surface groups in ICEM.

[ghorrocks]

ICEM is very different to ANSYS-Mesh. You will need to do the tutorials with ICEM to understand it. If all you are doing is just renaming faces so you can group them together and reduce the face count then the key areas you need to look at are parts and adding and removing items to parts. This is all in the ICEM tutorials. A lot of the tutorial will cover generating meshes - this is not relevant to this case.

[Gert-Jan]

- How did you generate the mesh?
- In ICEM, you need to create parts. To each part, you can add elements by picking, or box select, or ..... many more options...... When finished, export the mesh to ANSYS-CFX (.cfx5-file), and import it as ICEM-file in Pre.