Transfinite Mesh does not work with recombination

When I follow the tutorial ‘PrePoMax & CalculiX - Transfinite volume meshes’ with any version of PrePoMax that has transfinite meshing capability, I struggle at the point of recombining the tetra mesh. It simply doesn’t complete and throws an error in the log window, but nothing appears in the log files. I’m left with a tetra mesh.

I’m using Windows 10 Pro 22H2 with .NET Framework 4.8.9037.0 and the original CAD file ‘Gmsh_transfinite.STEP’ with the same setup as in the tutorial.
Do you have any idea what might be causing this issue?

Thanks

Daniel

1 Like

In log window states :
"11/22/24 15:05:46 Progress: Meshing order 2 (curvilinear off)…
11/22/24 15:05:46 Info: Done meshing order 2 (Wall 0.0111821s, CPU 0.015625s)
11/22/24 15:05:46 Info: Writing ‘C:\Users\Daniel\Downloads\PrePoMax v2.2.0\Temp\mesh.inp’…
11/22/24 15:05:46 Info: Done writing ‘C:\Users\Daniel\Downloads\PrePoMax v2.2.0\Temp\mesh.inp’

11/22/24 15:05:46 Elapsed time [s]: 0.3663461

11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘M3D9’ is not supported.
11/22/24 15:05:46 The element type ‘C3D27’ is not supported.

11/22/24 15:05:46 Mesh generation failed for part Solid_part-1. Check the geometry and/or adjust the meshing parameters."

Perhaps this is useful.

it seems not problem when i checked this feature in version 2.2.3dev, geometry built from scratch and imported as brep files.

1 Like

Yes, of course, it works, but for some reason, it doesn’t on my current Windows 10 installation. A colleague tested it in Wine on Linux, and it works there as well.

When I import the mesh.inp from the Wine version, everything is fine. However, the mesh.inp from the temp folder on my Windows 10 setup fails and throws the following exception: ‘The element type ‘M3D9’ is not supported,’ etc.

I have no clue why my Windows 10 is refusing to support this feature.

Do I have to Install certain things (gmsh, special Framework etc.)?

If the mesh contains C3D27 elements this means it produces the full finite elements which are not supported by PrePoMax. PrePoMax supports only C3D20 elements. The command that should force the GMSH to do that in the PrePoMax code is:

Gmsh.Option.SetNumber(“Mesh.SecondOrderIncomplete”, 1);

Do you have basic Gmsh installed? Maybe this setting is saved somewhere.

You could try to create a linear mesh instead of second order mesh (Meshing parameters → Second order → No) and change the Midside nodes on geometry setting.

2 Likes

No, I haven’t installed Gmsh before. Creating a linear mesh and changing the midside nodes didn’t help. I also tried it on my son’s gaming machine, and it worked there. I might end up reinstalling Windows 10.

Wait! :slight_smile: Try this first:

In gmsh standalone, If you have set Element order 2 as default and did not tick the box “use incomplete elements” and saved this as default options, the error occurs in prepomax.
So you need to select “use incomplete elements” or change the default to Element order 1.
Changing between these two settings seem also to have an effect of the resulting mesh element size in prepomax (I updated the mesh in prepomax without changing the size):

2 Likes

Downloading a standalone version of Gmsh and selecting ‘incomplete elements’ while saving the option as default worked for me. I can’t remember ever installing Gmsh as a standalone before, but I must have at some point. This aligns with what Matej mentioned earlier—there might be a saved setting somewhere in the system.

Where can I find this setting?

Awesome, Gunnar! You saved me a ton of time! Thanks, man!

1 Like

I found it:
C:\Users\username\AppData\Roaming\gmsh-options and C:\Users\username\AppData\Roaming\gmshrc.

Maybe there should be a check in PrePoMax to see if those settings exist.

But what I don’t understand is, doesn’t PrePoMax use its own local version of Gmsh? Or is it writing its own options file, with both the standalone Gmsh and PrePoMax overwriting it each time?

1 Like

this is what i understand, so i’m just taking a simple test from scratch and different file formats. Indeed, your log reported indicate complete quadratic were not supported. Also, generate extra membrane element (complete) in normally of transfinite solid mesh should not, probably.

previously, testing with second order is working fine on my machines (Win7 Pro),

1 Like

PrePoMax uses its own version of Gmsh and uses it using an API interface. I am also surprised that settings in these files override the settings PrePoMax sets using:

Gmsh.Option.SetNumber(“Mesh.SecondOrderIncomplete”, 1);

1 Like

Ok, and then what should be the next step?

1 Like

I am surprised that using linear mesh did not work. There should be no difference in using incomplete or complete elements.

1 Like

Ok, and then what should be the next step?

If I had to tackle the problem, I would suggest modifying the file according to one’s needs while saving the old version in a temporary file, and then restoring it after completing the mesh.

Hm, changing the existing files is risky. What if PrePoMax crashes before the files are changed back to the original settings? I think there should be another solution to force Gmsh to use local and not global settings.

Not risky if the configuration files are stored on disk beforehand. If this process is disrupted, the original files remain untouched.

But of course, it would be a clean soloution, to force gmsh to use local settings.

I reproduced the problem you had and the file gmsh-options is to blame. I opened an issue on the Gmsh page and we will see what happens.

1 Like

Since there is not much I can do I am moving the topic to General questions.

Daniel, tive uma situação similar. No meu caso, descobri que era o nome do caminho no qual a pasta “.zip” foi descompactada. No caminho (path) tinha um caractere como: ç, ã e outros. Coloquei a pasta descompactada diretamente em "c:\ " e funcionou. Na versão v2.3.4 dev mostra essa mensagem.

Daniel, I had a similar situation. In my case, I discovered that it was the name of the path in which the “.zip” folder was unzipped. In the path there was a character like: ç, ã and others. I put the unzipped folder directly into “c:\” and it worked. Version v2.3.4 dev shows this message.



This check was added to help solve such path problems.