#1 2023-02-14 20:40:18

jacob

Member

From: Dolní Benešov

Registered: 2022-03-07

Posts: 158

salome GMSH

Hello, is anyone able to create reasonable hex meshes in SMESH using GMSH?
I have tried a lot of different combinations of parameters but I get useless 3D meshes.

Last edited by jacob (2023-02-14 20:41:33)

Irvise

Member

Registered: 2019-12-07

Posts: 140

Re: salome GMSH

Hi Jacob,

afaik, Hex meshes in GMSH are still a work-in-progress. GMSH does not have a robust algorithm to create them... They somewhat recently added a very nice 2D Quad algorithm that produces very high quality 2D meshes, however, Hex is still not there yet.

My most successful Hex meshes where done by carefully partitioning the geometry and using the I,J,K algorithm

Best regards,
Fer

jacob

Member

From: Dolní Benešov

Registered: 2022-03-07

Posts: 158

Re: salome GMSH

Yes 2D meshes are better than using netgen however when I try to do extrude I usually get an error saying Error : No mesh elements assigned to a Sub-shape
With netgen there is no problem.

I just wonder why there are algorithms for 3D hex meshes, because when I tried to used them I get meshes that are really bad.

Irvise

Member

Registered: 2019-12-07

Posts: 140

Re: salome GMSH

Hi Jacob,

without your mesh and geometry it is quite difficult to understand what you are trying to do and what is failing. If you generate a 2D flat (or mostly flat) mesh, extrusion should just work within the SMESH module. One just has to select the direction line and that should be it.

I just read the Salome 9.10 release and it says that 3D GMSH can be used with a different 2D algorithm (if I understood it correctly). Maybe 2D GMSH cannot be used with a different 3D mesher. And some hex meshers may require a specific set of 2D mesh setups, so that may be what is failing.

Also, what version of Salome are you working with? Maybe using the latest Salome_Meca or Salome 9.10 could fix your issues as they have more features and fixes.

Best regards,
Fer

jacob

Member

From: Dolní Benešov

Registered: 2022-03-07

Posts: 158

Re: salome GMSH

Hello,
of course manual extrusion or rotation works, but then you loose associativity with a geometry.

Well, I found out extrusion works if I project source face on a target (however with netgen I don't have to do that)

I am using latest salome.

Maybe would be nice if someone or you could also share some examples.