Step requirements for meshing


#1

Hi guys,
i was trying to simulate an old Frontwing and Rearwing to get a comparison to other programs. I imported it as step. I prepared it as volume, so there should be no problems, but meshing it is not possible for me. Maybe its because of the winding profile witch made problems in other programs too.

So here my question:
What requirements should a step file fulfill, so that i can work with it in simscale?
What can make problems, what should i avoid, … ???

As addition my error messeges:
Illegal triangles were found after surface tesselation. There could be a problem with the CAD geometry. Trying to proceed anyway.

The tesselated surface is not closed. There could be a problem with the CAD geometry (such as self-intersections). Please inspect your geometry. Trying to proceed anyway.

The machine ran out of memory. Please choose a larger machine for computation.

In ANSYS i could run this step file after some small adjustments…

Thx for ur help :wink:


#2

Good evening @dwagner,

It seems that you have a memory problem where @afischer might give you a little more information.

@afischer posted a good answer to your question a while ago:

The hexahedral meshing is not based on so called rich geometry formats as for example *.step or .iges, but on triangulated geometries like e.g. *.stl. In general you should not care about this at all as the triangulation is done automatically prior to the meshing. In some cases, if the geometry model is not "clean", the triangulation can not be done properly and there might be small cracks or duplicated triangles. The meshing is in general very robust in regards to those defects.

Please also consider: CAD Preparation

If you still encounter any problems feel free to ask me.

Best,

Jousef


#3

Hey @dwagner,

as @jousefm mentioned the error that you experience is caused by a lack of memory on the computing instance. The warnings that you can see in the event log are just additional information as the mesh might be influenced in a negative way by those defects in the geometry, but it does not need to necessarily fail.

In your case you can see at the end of the meshing log that right before the meshing failed the meshing algorithm reported the following amount of cells per refinement level:

After balancing surface refinement iteration 3 : cells:23931933 faces:78383771 points:30768768
Cells per refinement level:
0 189888
1 8723
2 32235
3 127338
4 599305
5 2399851
6 12507644
7 3595245
8 4471704
Surface refinement iteration 4

which adds up to 23931933 total cells. This is a very high number. You can of course now use a 32 core instance instead (the available memory will be approximately doubled), but keep in mind that the computational costs of your simulation will scale with the mesh size. So you might want to adapt your mesh settings if possible. It is always a trade off.

Hope that helps!

Best Alex