[Gmsh] How to set element size on the surface of a cylinder in OpenCascade?

[Christophe Geuzaine]

> On 1 Aug 2019, at 20:07, Kópházi József <j.kophazi at imperial.ac.uk> wrote:
> 
> Dear Gmsh community,
> 
> I'm fighting with Gmsh to set up a model of a quarter cylinder using the new OpenCascade based facilities. The following script is considered:
> 
> SetFactory("OpenCASCADE");
> 
> cylinder = newv;
> Cylinder(cylinder)         = {  0.0  ,  0.0  ,  0.0  ,  0.0  ,  0.0  ,  60.0,  175.0  };
> box = newv;
> Box(box)                 = {  0.0  ,  0.0  , -50.0 ,200.0  , 200.0  ,200.0  };
> lst() = BooleanIntersection { Volume{ cylinder }; Delete; } 
>                             { Volume{ box }; Delete; };
> pt_volume = lst[0];
> 
> Characteristic Length{ PointsOf{ Volume{:}; } } = 6.0;
> 
> 
> However, the surface mesh on the (remaining part of the) cylinder is rather odd, it contains one single layer of elements axially. (Please find attached the image).
> 

It's a bug in the MeshAdapt algorithm. Using the frontal algo (Mesh.Algorithm = 6) gives the expected result.

Can you open an issue in our gitlab so we can track this problem?

Thanks,

Christophe



> <bghpnghkeenmmnod.png>
> 
> How could I get a proper, isotropic mesh?
> 
> Thank you for your help in advance,
> 
> Jozsef
> 
> 
> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine