Hello,
I am trying to mesh a volume with a certain refinement near one of its surfaces. It works perfectly with a cube (see image1) when I use the preferences shown in image 2.
However, when I mesh an irregular volume with the same procedure, the refinement does not propagate into the bulk and only takes place on the selected surfaces (see image 3).
I wonder how I can solve this problem. Thank you.
Mesh refinement
Moderator: GiD Team
Mesh refinement
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- cube.png (67.08 KiB) Viewed 6660 times
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- config.png (18.94 KiB) Viewed 6660 times
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- badmeshing.png (75.91 KiB) Viewed 6660 times
Re: Mesh refinement
The assignment of mesh sizes works in the same way in a shape of a cube or in another generic shape (for GiD the cube is not a cube, it's a generic volume).
Probably your problem is that you must assign appropiated sizes also to lines, not only to surfaces (the mesh of the surface depends on the mesh of its lines, and the mesh of the volume depends on the mesh of its surfaces).
And you are using transition parameter=0, I recommend a bigger value, e.g. 0.5 to allow a faster transition of sizes from small to big (a parameter=0 coult be too restrictive and the small size can't grow to the other assigned sizes of the general meshing size)
Only with the view of the image 3 I am unable to understand how is your geometry and the mesh, and which are your applied sizes.
Probably your problem is that you must assign appropiated sizes also to lines, not only to surfaces (the mesh of the surface depends on the mesh of its lines, and the mesh of the volume depends on the mesh of its surfaces).
And you are using transition parameter=0, I recommend a bigger value, e.g. 0.5 to allow a faster transition of sizes from small to big (a parameter=0 coult be too restrictive and the small size can't grow to the other assigned sizes of the general meshing size)
Only with the view of the image 3 I am unable to understand how is your geometry and the mesh, and which are your applied sizes.
Re: Mesh refinement
I have tried again relaxing the transition parameter and assigning a small element size to the lines and points of the surface but it did not work either.
Below you will see the problem, which perhaps was not clear enough with the previous picture. The size assigned to the refined curved surface, as well as its lines and points, is 0.0001, whereas the bulk has been assigned a size of 0.0005. However, it can be clearly seen how the 0.0001 size is only applied to the surface. The first row of elements just below does not see any refinement in the normal direction and the transition between one size and the other is not performed.
Below you will see the problem, which perhaps was not clear enough with the previous picture. The size assigned to the refined curved surface, as well as its lines and points, is 0.0001, whereas the bulk has been assigned a size of 0.0005. However, it can be clearly seen how the 0.0001 size is only applied to the surface. The first row of elements just below does not see any refinement in the normal direction and the transition between one size and the other is not performed.
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- badmeshing2.png (55.72 KiB) Viewed 6643 times
Re: Mesh refinement
attach a zip with your model
Re: Mesh refinement
This is the model. The mesh needs to be generated again.
- Attachments
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- fricative_real4_nomesh.gid.tar.gz
- (550.38 KiB) Downloaded 358 times
Re: Mesh refinement
When meshing, first is tried to generate the volume mesh with the selected 'Advanding front method', but this method is failing, and then GiD automatically try other method: Delaunay (Tetgen), and the resulting volume mesh doesn't has as good size transitions as the advancing front.
It is possible to force GiD to not try to use other method than the selected.
to do it set the GiD variable 'OnlyUseSelectedMesherVolumes' to 1
(e.g. writting this in the command entry: -np- GiD_Set OnlyUseSelectedMesherVolumes 1)
and you will notice than the advancing front volume mesher will fail in this case.
Is seems that the fail is related with some tolerances.
If do you scale for example your model x1000
Utilities->Move... (volumes, scale, scale value=1e3
Note: the mesh sizes assined to entities are also automatically scaled also.
and generate the mesh with equivalent general size (multiplied by the same scale 1e3) then the mesh could be generated and it looks more like you expected.
It is possible to force GiD to not try to use other method than the selected.
to do it set the GiD variable 'OnlyUseSelectedMesherVolumes' to 1
(e.g. writting this in the command entry: -np- GiD_Set OnlyUseSelectedMesherVolumes 1)
and you will notice than the advancing front volume mesher will fail in this case.
Is seems that the fail is related with some tolerances.
If do you scale for example your model x1000
Utilities->Move... (volumes, scale, scale value=1e3
Note: the mesh sizes assined to entities are also automatically scaled also.
and generate the mesh with equivalent general size (multiplied by the same scale 1e3) then the mesh could be generated and it looks more like you expected.