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Problem with `Form Union`in Building Geometry

Posted May 30, 2012, 11:12 a.m. EDT Geometry, Materials, Parameters, Variables, & Functions Version 4.2a 2 Replies

Wy Zhang
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Hi,

I have a question about building a geometric shape in v4.2a.

My model contains 2 cylinders jointed by a sphere. I used intersection and difference to get rid of the overlapping parts and formed a continuous shape. However, the finalization method ``Form a union`` gives me an error `Internal error in geometry decomposition.``, and only 1 cylinder appears to be available when the Material node is selected.

Does anyone know why this error occurs and how you would fix it?

Thanks in advance!
2 Replies Last Post May 30, 2012, 4:51 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 30, 2012, 2:32 p.m. EDT
Hi

No, not really. My experience is that intersections of spheres and cylinder, or any object of revolution, specially when close to tangeant are always delicate.

Anyhow, why split and join ? you can normally leave them intersecting, COMSOL will make a few extra domains, with internal "continuity" boundaries, and these will perhaps interfer a little with your meshing, but this should in now way interfer with the validity of the results. At most requiring a few extra clicks to select them all for the materials

--
Good luck
Ivar
Hi No, not really. My experience is that intersections of spheres and cylinder, or any object of revolution, specially when close to tangeant are always delicate. Anyhow, why split and join ? you can normally leave them intersecting, COMSOL will make a few extra domains, with internal "continuity" boundaries, and these will perhaps interfer a little with your meshing, but this should in now way interfer with the validity of the results. At most requiring a few extra clicks to select them all for the materials -- Good luck Ivar
Wy Zhang
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Posted: 1 decade ago May 30, 2012, 4:51 p.m. EDT
Thank you very much!
That was really helpful!
Thank you very much! That was really helpful!

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