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<p style="margin-top:0; margin-bottom:0">Dear Christophe,</p>
<p style="margin-top:0; margin-bottom:0">as you asked in your previous email, I have been testing the newly implemented quad-boundary recovery in Gmsh (at that time it was the development version, future 4.0.5 or 4.1).</p>
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<p style="margin-top:0; margin-bottom:0">I found that Gmsh works fairly well, succeeding to generate a valid mesh with sufficient overall quality (a few ill-shaped elements may be present depending on the geometry configuration).</p>
<p style="margin-top:0; margin-bottom:0">However, in some cases, the resulting mesh has a negative cell. All the failing cases have one negative cell only, this cell always being a flat pyramid
<span>(see attached picture)</span>. It looks like <span>the vertex relocation</span> cannot move the top of the pyramid inside the volume.
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<p style="margin-top:0; margin-bottom:0">Does anyone have reported a similar behaviour?</p>
<p style="margin-top:0; margin-bottom:0">If necessary, I can provide you with a failing test case.<br>
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<p style="margin-top:0; margin-bottom:0">Regards,</p>
<p style="margin-top:0; margin-bottom:0">Simone G.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Christophe Geuzaine <cgeuzaine@uliege.be><br>
<b>Sent:</b> Monday, November 12, 2018 3:33:25 PM<br>
<b>To:</b> Simone GREMMO<br>
<b>Cc:</b> gmsh@onelab.info<br>
<b>Subject:</b> Re: [Gmsh] Gmsh-4.0.4 Volume mesh issue</font>
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Dear Simone,<br>
<br>
Indeed, Gmsh 4.0.0 -> 4.0.4 do not have the ability to automatically create hybrid tetrahedral+pyramidal meshes (your surface contains quadrangles).<br>
<br>
The latest snapshot (future Gmsh 4.0.5 or Gmsh 4.1) has a new algorithm to generate such meshes, similar but more general to what we did in Gmsh 3. Give it a try and let us know how it works out for you?<br>
<br>
Christophe<br>
<br>
<br>
> On 12 Nov 2018, at 14:38, Simone GREMMO <Simone.GREMMO@umons.ac.be> wrote:<br>
> <br>
> Dear all, <br>
> I have just downloaded the last version of Gmsh (4.0.4), but I am facing a problem with the generation of a "simple" volume mesh.<br>
> <br>
> I would like to mesh a volume delimited by a surface mesh in .msh format, but it looks like Gmsh cannot create the volume mesh.<br>
> Error Message is :<br>
> .....<br>
> Info : Boundary Recovery...<br>
> Info : Writing to GRegion...<br>
> Info : Reconstruct time : 0.116395 sec<br>
> Error : No tetrahedra in region 5<br>
> Info : 3D point insertion terminated (3195 points created):<br>
> Info : - 0 Delaunay cavities modified for star shapeness<br>
> Info : - 0 points could not be inserted<br>
> Info : - 0 tetrahedra created in 1.6e-05 sec. (0 tets/sec.)<br>
> Error : No tetrahedra in region 5 <br>
> Info : Done meshing 3D (0.133228 s)<br>
> Info : 4857 vertices 6617 elements<br>
> Error : ------------------------------<br>
> Error : Mesh generation error summary<br>
> Error : 0 warnings<br>
> Error : 2 errors<br>
> Error : Check the full log for details<br>
> Error : ------------------------------<br>
> <br>
> I am attaching the .geo file I have created as well as the surface mesh I used. To launch the mesh generation I run the command:<br>
> gmsh-4.0.4 createGeom.geo -3 -o volumeMesh.msh<br>
> <br>
> Note that the same test case is successfully meshed using Gmsh version 3.0.6.<br>
> <br>
> Do you have any suggestion on how to solve the problem? <br>
> Is it possible that the surface mesh, containing both triangles and quadrangles is at the origin of the problem?<br>
> <br>
> Thanks in advance for your suggestions.<br>
> Regards,<br>
> Simone G.<br>
> <br>
> <createGeom.geo><surfaceMesh.msh>_______________________________________________<br>
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Prof. Christophe Geuzaine<br>
University of Liege, Electrical Engineering and Computer Science <br>
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