[Gmsh] anisostropic meshing / bamg algorithm

Wed Feb 29 13:54:33 CET 2012

Hi Martin,

I have downloaded the sources via svn and also searched in the tgz nightly source snapshot, but there is neither a “benchmarks” directory nor a file called CubeAniso.geo. Could you tell me where to find it, or send it to me? A working example would be very helpful as I have no idea how to use anisotropy, and I am not going to delve in to the gmsh sources.

Thank you,

Matthias

Von: Zenker, Dr. Matthias [mailto:Matthias.Zenker at erbe-med.com]
Gesendet: Donnerstag, 16. Februar 2012 15:42
An: 'Martin Vymazal'; gmsh at geuz.org
Betreff: Re: [Gmsh] anisostropic meshing / bamg algorithm

Hi Martin,

thanks for the pointers. I will try them out and may come back with more questions in 10 days or so (on vacation next week… ;) )

Matthias
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Von: Martin Vymazal [mailto:martin.vymazal at vki.ac.be]<mailto:[mailto:martin.vymazal at vki.ac.be]>
Gesendet: Donnerstag, 16. Februar 2012 14:21
An: gmsh at geuz.org<mailto:gmsh at geuz.org>
Betreff: Re: [Gmsh] anisostropic meshing / bamg algorithm

Hello Matthias,

you can specify the entries of the mesh metric using a field which is called 'MathEvalAniso'. In case you have svn sources of gmsh, you can find an example using MathEvalAniso in GMSH_SOURCE_ROOT/benchmarks/3d/CubeAniso.geo

The source code of this field is in Mesh/Field.[h/cpp]

Some more examples concerning background fields and their usage are also available in gmsh reference manual.

Best regards,

Martin Vymazal

On Thursday 16 February 2012 13:05:33 Zenker, Dr. Matthias wrote:

Hi Martin,

thank you for your answer. How do I define such an anisotropic mesh size field? Do you have a short example, or is this described somewhere? I did not find it in the Reference manual.

Best regards,

Matthias

Von: Martin Vymazal [mailto:martin.vymazal at vki.ac.be]<mailto:[mailto:martin.vymazal at vki.ac.be]>
Gesendet: Donnerstag, 16. Februar 2012 12:17
An: gmsh at geuz.org<mailto:gmsh at geuz.org>
Betreff: Re: [Gmsh] anisostropic meshing / bamg algorithm

Hello Matthias,

you can use the bamg algorithm by calling 'gmsh -2 -algo bamg my_file.geo' from command line. For 3d anisotropic mesh, you do the same with '-3 -algo mmg3d'.

You need to supply a mesh size field which will tell the anisotropic algorithm in which direction to refine the mesh.

Best regards,

Martin Vymazal

On Thursday 16 February 2012 10:56:06 Zenker, Dr. Matthias wrote:

Hi,

does anyone have an answer to the question below?

It was said that an anisotropic mesh can be achieved using the bamg algorithm. I have some questions:

1.                   My 3D geometry consists of several layers stacked in z direction. Some of these layers are rather thin. I would like to have a mesh which is finer in z direction than in x and y direction. Can this be achieved using the bamg algorithm? If so, how?

2.                   How can I access this algorithm from the GUI? I did not find it in Options – Mesh.

3.                   If not accessible from the GUI, how else can I use it?

4.                   Is there any documentation available concerning this topic? I did not find anything in the gmsh manual (which is from October 2010 btw).

Thank you,

Matthias

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