[boffin5]

Hi,

I am posting this Salome related question because in the past I have gotten valuable help from this forum. It's a meshing question that should be general in nature.

My project as of now is to learn how to do meshing in Salome, and use the results in OpenFOAM. I am working with a generic racecar body, which I import as an stl file. In the image, it appears in the top. Characteristic of stl files, it shows as a set of triangles. SnappyHexMesh in OpenFOAM would operate on these triangles, and the result would be a mesh including a lot of skinny triangles which would probably cause OF to choke.

Therefore, my hope is that tools such as Salome can provide more robust meshing capability than OF, so as to produce more regular cells, without all these skinny triangles. My notional goal is indicated in the lower right side of the image.

However, even after trying a variety of approaches with Salome, I still end up with the skinny triangles, as seen in the lower left of the image. It appears to still be operating on the triangles from the stl file. I know that people such as Tobi have much experience in this regard, and hope that I might receive advice to help me understand better procedures to follow.

[boffin5]

After churning through some youtube videos, I happened on this one: "Fixing Mesh in Salome".
It shows how to assess a mesh, and importantly, ways to fix the geometry to result in a mesh without errors.
First, in the geometry mode, I used Repair - Limit Tolerance. This found geometry elements in the stl file that were out of tolerance. Then, I created a mesh with 1D - 2D and edited the parameters.
This looks like it will work.

[joshwilliams]

I have no experience in SALOME, but I would probably recommend to first remesh the original STL file. If you have more regular triangles, I guess snappy will do much better. There are several python libraries like vedo and pyvista that may be able to do this.

[boffin5]

Thanks for the reply, Josh.
It turns out that in Salome you need to use a step file as a basis for meshing, not an stl file.
Stl files by their very nature have surfaces composed of triangles, which often are very slender, and this can cause problems in generating meshes with evenly distributed cells. SnappyHexMesh uses stl files in its processing, which is why I have been having problems when using it with more complicated geometries.
Salome was happy to import stl files, but the resulting mesh still had the slender triangles, whereas when I used step files, the results were much better.