[Gmsh] Meshing composite volumes

[Ted Kord]

Hi Martin,

This is great, thanks. You're right about the problem with the interior
volume and I'll see if I can plug the holes in the interior surface.

Again, many thanks,

Theodore




On 3 May 2013 10:40, Martin Vymazal <martin.vymazal at vki.ac.be> wrote:

> **
>
> Hello Theodore,
>
>
>
> I attached a geo file and a screenshot. If you're using linux, run as
>
> gmsh -3 remesh.geo output.msh
>
>
>
> I suppose this is not exactly what you wanted (the interior volume is not
> completely removed), and the problem most likely comes from the fact that
> the interior surface does not form a watertight mesh (has holes). Since the
> interior volume can 'communicate' with the surrounding volume through the
> holes, the mesh generator fills everything. The only option I see is making
> sure that the interior surface is really closed.
>
>
>
> Best regards,
>
>
>
> Martin Vymazal
>
>
>
>
>
> On Thursday 02 May 2013 12:41:18 Ted Kord wrote:
>
> Hi Martin
>
> Sorry for the late reply. I've attached the two surface meshes:
> polygon.stl and ellipsoid.stl. So, what I wanted to do was have a polygon
> mesh with the ellipsoid removed. Ideally, of course, I just would need to
> know the common surface shared by both the polygon and the ellipsoid in a
> 3D mesh.
>
> Could I ask that you please not share these meshes or post them on the
> forum as they are subject to some restrictions/copyright, etc. Of course,
> so that me and the gmsh community can learn, posting and sharing the geo
> file is a good thing.
>
> Many thanks,
>
> Theodore
>
>
>
> On 30 April 2013 22:03, Martin Vymazal <martin.vymazal at vki.ac.be> wrote:
>
> Hello Theodore,
>
>
>
> could you send me the stl files? If I manage to produce the mesh, I'll
> send the geo file to you.
>
>
>
> Best regards,
>
>
>
> Martin Vymazal
>
>
>
>
>
> On Tuesday 30 of April 2013 17:18:33 Ted Kord wrote:
>
> Hi Martin,
>
> Thanks. Is this what you mean?
>
>
> Merge "polygon.stl";
> Merge "ellipsoid.stl";
>
> CreateTopology;
>
> Physical Surface (1) = {1};
> Physical Surface (2) = {2};
>
>
>
> I'm not sure what to do after this to remove the ellipsoid from the
> polygon?
>
> Best regards,
>
> Theodore
>
>
>
> On 30 April 2013 15:18, Martin Vymazal <martin.vymazal at vki.ac.be> wrote:
>
> Hi Theodore,
>
>
>
> you need to tell gmsh that the surface contains a hole. Define two line
> loops - one for the contour of the external polygon (say Line Loop 1) and
> one for the contour of the ellipse (say Line Loop 2). Then you define your
> surface for meshing as
>
>
>
> Plane Surface(1) = {1,2}; // Subtract the interior of line loop 2
>
> // from the interior of line loop 1
>
>
>
> See section 5.1.3 in gmsh reference manual or tutorial 3 on gmsh website.
>
>
>
> If you don't have any lines to create line loops from (since you're
> loading an stl file), take a look at 'CreateTopology'.
>
>
>
> Best regards,
>
>
>
> Martin Vymazal
>
>
>
> On Tuesday 30 April 2013 12:32:34 Ted Kord wrote:
>
> Hi,
>
> I have an STL mesh consisting of an irregular ellipsoid in an irregular
> polygon. When I turn off 'surface faces' in the 'Options - Mesh', I can see
> the ellipsoid in the polygon. What I'd like to do is mesh just the
> containing polygon excluding the ellipsoid, i.e., the final mesh will have
> a hole where the ellipsoid should be. How can I do this in gmsh?
>
>
> --
> Best regards,
>
>
> Theodore
>
>
>
>
>
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>
>
>
> --
> Best regards,
>
>
> Theodore
>
>
>
>
>
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>
>
>
> --
> Best regards,
>
>
> Theodore
>
>
>
>
>
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-- 
Best regards,

Theodore
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