Meshing and Connecting Parts from .stl Files

[LP1012]

Hello,

I have created a CAD model the includes different materials and structures. As in, this CAD model has multiple bodies in the file, and each body (and its mesh) can be easily exported as a .stl file (though there are many options for this). Since each body will have different materials and perhaps different physics kernels assigned to it, I would like to see about importing each separately to its own Mesh object in MOOSE.

My questions are thus:

1. Would this method be recommended to ensure that the input file is kept clean and organized?
2. Since .stl files only contain the mesh, not the boundary names, is there a streamlined/easy way to import these meshes and assign boundary names for future boundary condition assignments?
3. Instead of meshing separately, say using Gmsh or another utility, could MOOSE simply import the CAD file (in whatever format is needed) and mesh within MOOSE, again assigning boundary names? If so, are there any controls over the type of mesh (tetrahedrals vs hexahedrals)?

Thank you very much in advance!!!

P.S. For reference I have included an image of the CAD model, which was created with FreeCAD. Though relatively simple, I am hoping to grow the model and design over time.

[GiudGiud]

Hi

Would this method be recommended to ensure that the input file is kept clean and organized?

likely not. Importing the mesh in one FileMeshGenerator will make your Mesh block fairly tidy.
However, each part should be its own subdomain so you can assign equations and materials on a per-subdomain basis.
Importing each part separately would also not easily get the mesh connectivity you need for most physics. There are ways around non-conformal meshes for some physics but not all.

Since .stl files only contain the mesh, not the boundary names, is there a streamlined/easy way to import these meshes and assign boundary names for future boundary condition assignments?

stl files contain the CAD, not really the mesh. In your meshing tool, I think FreeCAD, you assign the boundary names then export it to a mesh format. This export should conserve the boundary names you assigned, but it's worth checking in Paraview if it did.

Instead of meshing separately, say using Gmsh or another utility, could MOOSE simply import the CAD file (in whatever format is needed) and mesh within MOOSE, again assigning boundary names? If so, are there any controls over the type of mesh (tetrahedrals vs hexahedrals)?

not at the moment. Support for meshing clean STL files is not very far away though, and we would be able to create a tet mesh there.
Feel free to create a feature request on the libmesh repo.

Guillaume

[LP1012]

Thank you!

Would you know of any example input files in MOOSE repo that I could look at for reference, specifically for assigning different materials and kernels to different subdomains?

[GiudGiud]

see test/tests/./materials/active_material_props/check_active_props.i