Dear Max, dear Christophe,
thank you for the fast answers. As it turned out I made a stupid mistake
and forgot to replace a symbolic link still pointing the gmsh 3.0.6
executable, while it actually should have pointed to the fresh
downloaded binary of 4.0.4. This now gives me the same meshes after
running gmsh in batch mode several times. However, adding your
Mesh.RandomFactor entries did not reproduce the surface mesh warning on
my machine.
Thanks a lot,
Thomas
Am 2018-10-27 09:56, schrieb Christophe Geuzaine:
On 27 Oct 2018, at 00:16, Max Orok <[email protected]> wrote:
Hi Thomas,
I first tried to set the random factors using:
Mesh.RandomFactor = 1e-9;
Mesh.RandomFactor3D = 1e-9;
I think the bug is elsewhere however...
With your file, I get a warning the first time and none the subsequent
times.
I think it is due to internal state with the mesher remembering the
choice of MeshAdapt?
Yes : when meshing fails with Delaunay or Frontal we currently force
MeshAdapt on that surface. Currently this choice is persistent (in a
Gmsh run) - I will change this so that the initial state is restored.
Switching from Delauney to MeshAdapt halfway might cause different
point spacing etc.
Here are some pictures showing the two consecutive mesh logs
1st time:
<image.png>
2nd time (same window):
<image.png>
On closing Gmsh and trying again, this repeats.
Instead, to fix your problem, you can set the meshing algo to
MeshAdapt ahead of time by changing the line here:
Mesh.Algorithm = 1; // changed to MeshAdapt
Three repeated trials gave identical output files.
p.s. just in case, all of the current / modified options can be looked
through and searched using Ctrl-Shift-H or Help -> Current Options and
Workspace
Sincerely,
Max
On Fri, Oct 26, 2018 at 12:44 PM, Thomas Kiel
<[email protected]> wrote:
Dear Gmshers,
as I already pointed out in an earlier email (s.
http://onelab.info/pipermail/gmsh/2018/012045.html), I had problems
with reproducing the exact same mesh twice. Since this email was
unfortunately html encoded I think it was overlooked. Yet I like to
apologize to ask again, this time in text formatted email, how to set
the random number generator seed with an outside option?
I know, that a grep to "srand" within the gmsh git repository gives
several times hard-coded initialized seeds, e.g.
Geo/SOrientedBoundingBox.cpp:326: srand((unsigned)time(0));
Mesh/Levy3D.cpp:624: srand(time(NULL));
Mesh/Levy3D.cpp:1359: srand(time(NULL));
Mesh/meshGFaceRecombine.cpp:245: srand(time(NULL));
Mesh/meshGFaceLloyd.cpp:394: srand(time(NULL));
yet I am not sure whether these influence my mesh generation. A
minimalistic test file which causes different meshes at consecutive
runs in my case, is
//+
SetFactory("OpenCASCADE");
Mesh.CharacteristicLengthMin = 0.001;
Mesh.CharacteristicLengthMax = 2.0;
Mesh.CharacteristicLengthExtendFromBoundary = 1;
Mesh.Algorithm = 5;
Mesh.Smoothing = 3;
Mesh.Algorithm3D = 1;
Box(1) = {0, -0.5, -0.5, 1, 1, 1};
Box(2) = {-1, -0.5, -0.5, 1, 1, 1};
Sphere(3) = {0.5, 0.0, 0.0, 0.3, -Pi/2, Pi/2, 2*Pi};
Coherence;
surfs_box1() = Unique(Abs(Boundary{ Volume{4}; } ));
lines_box1() = Unique(Abs(Boundary{ Surface{surfs_box1()}; } ));
pts_box1() = Unique(Abs(Boundary{ Line{lines_box1()}; } ));
surfs_sphere() = Unique(Abs(Boundary{ Volume{3}; } ));
lines_sphere() = Unique(Abs(Boundary{ Surface{surfs_sphere()}; } ));
pts_sphere() = Unique(Abs(Boundary{ Line{lines_sphere()}; } ));
surfs_box2() = Unique(Abs(Boundary{ Volume{2}; } ));
lines_box2() = Unique(Abs(Boundary{ Surface{surfs_box2()}; } ));
pts_box2() = Unique(Abs(Boundary{ Line{lines_box2()}; } ));
// sorted from largest to smallest:
Characteristic Length{pts_box2()} = 0.5;
Characteristic Length{pts_sphere()} = 0.2;
Characteristic Length{pts_box1()} = 0.1;
I tested this on a machine running Ubuntu 16.04 and installed the
out-of-the-box gmsh 4.0.4 version from the webpage. If any further
detail on the running machine is required please tell me.
I hope you can help me out.
Thanks a lot in advance and best regards,
Thomas Kiel
--
Thomas Kiel
Theoretische Optik und Photonik
Humboldt-Universität zu Berlin, Institut für Physik
Newtonstraße 15, 12489 Berlin
Tel.: +49 30 2093 7999
E-Mail: [email protected]
Web: https://top.physik.hu-berlin.de/people/thomas-kiel
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--
Max Orok
Contractor
www.mevex.com
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—
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
Free software: http://gmsh.info | http://getdp.info |
http://onelab.info
--
Thomas Kiel
Theoretische Optik und Photonik
Humboldt-Universität zu Berlin, Institut für Physik
Newtonstraße 15, 12489 Berlin
Tel.: +49 30 2093 7999
E-Mail: [email protected]
Web: https://top.physik.hu-berlin.de/people/thomas-kiel
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