[Gmsh] Defining a cylinder inside a cube using extrude command

[sharma.abhi.itbhu at gmail.com]

Hello GMSH users,

        I am new to GMSH, I am trying to create a small cylindrical object
inside a cube. I create the cylinder using Extrude command and a cube
outside it. When I tried to mesh this geometry, I cylindrical objects are
mesh properly inside but it only creates the surface mesh on the cube.

I think the problem is I am not able to  define a volume of cube excluding
the cylinder. I looked at the examples (older posts) / tutorials, where the
surface after the extrusion command is defined. I am unable to understand
how these numbers for the different surfaces are defined.

Please have a look at the attached file, where I am trying to create two
cylinders inside a cube. It will be nice if someone can explain how to get
the correct mesh (numbering scheme after extrude command).


Thanks,

Best Regards,

Abhishek
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