[Gmsh] question about CharacteristicLengthMax

[Christophe Geuzaine]

> 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.

Christophe

> 
> 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
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine