Hello All,
I am using Gmsh for creating a finite element mesh. After I create the volume mesh, Is there a way to do a local mesh refinement around a particular point (say x,y,z) and within a sphere of given radius.
A bit of detail :
To start with , I DONOT have any geometry with me that makes it hard. I start with many .stl files that I obtain from another software (Dream 3D) and make a volume mesh using Gmsh.
Now with this .msh file without having the geometry, Is it possible to refine locally ?
Kindly help !
-Prithivi
Hello Prithivi,
I went through the same issue a couple of years ago, but the Youtube video below really help me in solving it. Hope it helps you too.
https://www.youtube.com/watch?v=kpWVNNHHdd8
Best wishes
Musa
Hello Musa,
Thanks a lot for your reply. I would like to explain my problem a bit further.
To start with , I DONOT have any geometry with me that makes it hard. I start with many .stl files that I obtain from another software (Dream 3D) and make a volume mesh using Gmsh.
Now with this .msh file without having the geometry, Is it possible to refine locally ?
You help would be greatly appreciated.
Thanks,
Prithivi
You can add points in the regions you want refined. When you add a point to your model, one of the parameters you can give is the characteristic length at that point. GMSH will use this when meshing as a constraint on the mesh size in the vicinity of the point. Add as many points as you need in the regions of interest, to coerce GMSH into giving you approximately that characteristic length size in those regions.
For those who end up here, there is also a channel for #gmsh on Elmer's Discord server
https://discord.gg/SXxvTqg
May I ask a follow-up - when I use David's method of inserting points but find points on the boundary which gmsh then has problems with. Any ideas how to add points that end up intersecting a boundary?
The method described above (enforcing a new point geometric entity to then prescribe a mesh size on it) only allows to refine in the vicinity of a point. In some occasions you need to refine entire regions and even control the field size gradients accurately. Gmsh allows all of that, it is in fact quite sophisticated. You can have refinement boxes, attractors and even define the mesh size based on pixels on a picture (useful if you have a background field which will influence your mesh size). I added a fun example, obtained from a comic strip picture.
I suggest looking into the gmsh manual section 6.3.1" Specifying mesh element sizes"
The tutorials are also a great tool to progress with gmsh, I use them a lot. See this tutorial for instance
https://gitlab.onelab.info/gmsh/gmsh/-/blob/master/tutorial/t10.geo
Hope that helps,
Hadrien
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