[Gmsh] question about CharacteristicLengthMax

Christophe Geuzaine cgeuzaine at uliege.be
Fri Oct 18 22:00:13 CEST 2019

> On 4 Oct 2019, at 05:54, Peter Johnston <p.johnston at griffith.edu.au> wrote:
> Hello,
> I was under the impression that CharacteristicLengthMax was used to control the mesh size in gmsh. However, I seem to he having some issues.
> In the attached python script, I read in some STL files that define surface. I then define some volumes and then mesh them. If I do not set CharacteristicLengthMax I get a volume mesh as shown in no-max.jpg. This is OK, but I would like some more nodes within and around my heart. If I set CharacteristicLengthMax=0.5, then I get a similar mesh around the heart, but it is finer away from the heart (max-0-5.jpg). However, if I set CharacteristicLengthMax=0.05, then I appear to get rubbish, especially around the heart (max-0-05.jpg).
> Clearly, I have missed something.

The STL mesh you merge will not be remeshed, so it constraints the volume mesh size. If you want to remesh the STL, see e.g. tutorial/t13.geo.


> I also tried to use a ball around the heart region, but that didn’t achieve anything. Given the above comments, I was unsure what to put in for VIN and VOUT.
> Any thoughts would be much appreciated.
> Thank you,
> Peter.
> ---------------------------------------------------------------------
> Associate Professor Peter Johnston (FAustMS, FIMA)
> School of Environment and Science
> Griffith University | Nathan | QLD 4111 | Technology (N44) Room 3.19
> T +61 7 373 57748| F +61 7 373 57656 Email p.johnston at griffith.edu.au
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Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 

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