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problems with rendering model : circular faces in geometry convert to squares

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Hello
I have created a geometry using comsol CAD in version 4.2a. I am solving an RF antenna problem.
The model is of a small device which is a 2.5cm long cylinder 3.5mm in diameter. The internals components of the
cylinder have very small(50um circular cross section) geometries. This small device is embedded in a much large cylinder 28cm long and 33 cm in diameter. The whole model is further placed inside a PML spehrical shell which is about 0.7meters. So basically the model has a wide dynamic range in terms of geometrical scale.

The problem occurred after completing the geometry construction successfully.
When I clicked 'Materials' to add materials to the model.
The tool gave warnings saying that multiple faces failed to render. Furthermore all the curves on the device (small device at the origin) changed from circular curves to square cross-sections. The model no longer has the circular curves that were modeled in the geometry. Also the model fails to mesh. The main problem is however the failure of the tool to render circular curves and instead use squares. This has caused various edges to impinge into each other: basically the geometry that the tool rendered internally is not what I created. The original geometry remains preserved when I click on 'geometry'

I tried searching through the knowledge base and found the following link:
www.comsol.com/support/knowledgebase/983/
I have tried some of the suggestions:
1) I switched from the COMSOL CAD module (in which i made the geometry) to the suggested CAD import module:
just as shown here: www.comsol.com/support/knowledgebase/1089/
This did not help
2) I am running the latest version of comsol 4.2a.
3) I made manual unions as shown in the model, suggested by the knowledge base: this did not help.
4) Regarding simplifying the geometry further:
I understand that my model has a large dynamic range in geometry sizes but it is as simplified as i can make it, and will not be able to remove features.
5) I have tried to use the 'assembly' feature where I chose 'Form an assembly' instead of 'form a union' I also deselected 'create pairs'. This did not help either.

Comsol is running on machine with 32GB of RAM so I really don't care about the model using too much memory or too much time to solve. My main goal is to get it to mesh and solve in the first place.

Any suggestions would be welcome.


1 Reply Last Post Apr 23, 2012, 1:10 p.m. EDT
COMSOL Moderator

Hello Harshit Suri

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Posted: 1 decade ago Apr 23, 2012, 1:10 p.m. EDT
Hi,

I have the same problem with curved geometries such as spirals.

how did you make manual unions? since I tried making unions manually but at the end when i wantred to define the material everything seemed to be mixed.nad defeent parts of the geometry seemd to be connected together such that by choosing one part other parts got chosen.
Did you find any solution to get rid of the rendering error?

Thanks,
Atefeh
Hi, I have the same problem with curved geometries such as spirals. how did you make manual unions? since I tried making unions manually but at the end when i wantred to define the material everything seemed to be mixed.nad defeent parts of the geometry seemd to be connected together such that by choosing one part other parts got chosen. Did you find any solution to get rid of the rendering error? Thanks, Atefeh

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