[Gmsh] Refine mesh via Gaussian rim inside disk

[Christophe Geuzaine]

> On 24 Apr 2020, at 09:21, Christophe Geuzaine <cgeuzaine at uliege.be> wrote:
> 
> 
> Hi Lars,
> 
> The default algorithm (Frontal-Delaunay) sometimes still has trouble with size fields with small features. You might want to use the Delaunay algorithm in such cases:
> 
> Mesh.Algorithm = 5;
> 
> (I will add a note in the documentation about this.)
> 
> For 3D meshes, the latest development snapshot includes mesh size field support in the new 3D algorithm HXT (Mesh.Algorithm3D = 10). Your feedback on this experimental support will be very welcome!
> 

At first sight it seems ok:


> Cheers,
> 
> Christophe
> 
> 
>> On 23 Apr 2020, at 17:54, Lars Hubatsch <hubatsch at pks.mpg.de> wrote:
>> 
>> Hi all,
>> 
>> I’m trying to create a disk mesh with a given background and, within a rim around the center, a local decrease of the characteristic length that follows a Gaussian (see attached image 1).
>> 
>> Code:
>> 
>> SetFactory("OpenCASCADE");
>> Disk(1) = {0, 0, 0, 4};
>> Physical Surface("surfacedomain") = {1};
>> 
>> Field[3] = MathEval;
>> Field[3].F = ".5 - (.5-0.01)*exp(-(1./0.1) *((sqrt(x*x+y*y)-1))*((sqrt(x*x+y*y)-1)))";
>> 
>> Background Field = 3;
>> 
>> However, for the parameters above the rim is not closed, what am I getting wrong?
>> If I change parameters slightly, e.g. 0.1 to 0.2 or 0.01 to 0.005 I get the correct representation. My problem is, that I eventually would like to do this in 3D within a sphere instead of a disk. However, this is visually harder to inspect (or is there a good way to do this?), so I would like to make sure that things work in principle in 2D.
>> 
>> Thanks,
>> Lars
>> 
>> <Screenshot 2020-04-23 at 17.54.29.png>
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> 
> — 
> Prof. Christophe Geuzaine
> University of Liege, Electrical Engineering and Computer Science 
> http://www.montefiore.ulg.ac.be/~geuzaine
> 
> 
> 

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



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