[Gmsh] Defining a small circle on a truncated cone

[Christophe Geuzaine]

> On 2 Oct 2018, at 17:10, Najib Alia <alia at wias-berlin.de> wrote:
> 
> Dear all,
> 
> I am trying to define a small circular area on the outer surface of a
> truncated cone, see file attached.
> 
> After defining some points for the circle on the outer surface, and
> using Ellipses and the feature "Points{...} In Surface{...}", the 3d
> mesh does not take into account the circle; only the points are
> correctly on the mesh.
> 
> It seems that the way I have built the circle is not correct: the circle
> does not follow the curvature of the cylinder.
> 
> How can I construct the circle so that it fits with the truncated cone
> and its volume mesh?

I would use the OpenCASCADE factory:

Simplest:

SetFactory("OpenCASCADE");
Cone(1) = {0,0,0, 0.5,0,0, 0.5,0.2, 2*Pi};
Sphere(2) = {0.2,0.4,0, 0.1};
BooleanFragments{ Volume{1}; Delete; }{ Volume{2}; Delete; }
Physical Volume(1) = {1,2};

A bit more involved:

SetFactory("OpenCASCADE");
Cone(1) = {0,0,0, 0.5,0,0, 0.5,0.2, 2*Pi};
Sphere(2) = {0.2,0.4,0, 0.1};
Delete{ Volume{1,2}; }
BooleanFragments{ Surface{1}; Delete; }{ Surface{4}; Delete; }
Recursive Delete { Surface{6, 7}; }
Surface Loop(10) = {2:5};
Volume(1) = {10};

etc.

Christophe


> 
> Thank you very much ahead for your help.
> 
> Best regards,
> 
> -- 
> 
> Najib Alia  
> MIMESIS PhD Student
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> 
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— 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine

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