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Problem in cylinder geometry

Posted Oct 19, 2011, 9:00 a.m. EDT Geometry 5 Replies

Gustavo Andrade
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Hello,

I'm a new user of Comsol and I have the following problem:
I'm is using a cylinder geometry with radius:0.013m and lenght: 172m when I build this geometry I dont have a cylinder in the grafics window but a rectangle. Why this is occuring?

5 Replies Last Post Jun 5, 2013, 2:05 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 Oct 19, 2011, 10:02 a.m. EDT
Hi

if you are in 2D-axi, you should only see a rectangle = cut view of your cylinder. The results will be projected onto a 3D view (if you are in 4.2 or later)
In 2D-axi do not forget (see the doc):
1) work only in the Right I-IV quadrant (only for r>0 =horizontal axis >0) remove/cut all geometry left for the axis line r=0
2) volume is a area *2*pi*r and line is a surface *2*pi*r in integrations

--
Good luck
Ivar
Hi if you are in 2D-axi, you should only see a rectangle = cut view of your cylinder. The results will be projected onto a 3D view (if you are in 4.2 or later) In 2D-axi do not forget (see the doc): 1) work only in the Right I-IV quadrant (only for r>0 =horizontal axis >0) remove/cut all geometry left for the axis line r=0 2) volume is a area *2*pi*r and line is a surface *2*pi*r in integrations -- Good luck Ivar
Gustavo Andrade
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Posted: 1 decade ago Oct 19, 2011, 10:54 a.m. EDT
Im using 3d view and comsol 4.2. In attach is a print screen of my tube.
I saw that if I use a lager radius of the tube the cilinder take your real form, but for small radius its a rectangle.
Im using 3d view and comsol 4.2. In attach is a print screen of my tube. I saw that if I use a lager radius of the tube the cilinder take your real form, but for small radius its a rectangle.

Attachments:

Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Oct 19, 2011, 11:53 a.m. EDT
Your cylinder has a very high aspect ratio. COMSOL by default does not accurately plot very small lines/surfaces (a very suitable setting for speeding up most 3D plots). You can override that by setting Detail = Fine under the Options menu > Preferences > Graphics. You may still run into trouble with meshing and analysis. If this is a solid consider defining a line instead and using beam elements.

Nagi Elabbasi
Veryst Engineering
Your cylinder has a very high aspect ratio. COMSOL by default does not accurately plot very small lines/surfaces (a very suitable setting for speeding up most 3D plots). You can override that by setting Detail = Fine under the Options menu > Preferences > Graphics. You may still run into trouble with meshing and analysis. If this is a solid consider defining a line instead and using beam elements. Nagi Elabbasi Veryst Engineering
Gustavo Andrade
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Posted: 1 decade ago Oct 19, 2011, 12:22 p.m. EDT
thx for the help.
thx for the help.
Mah
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Posted: 1 decade ago Jun 5, 2013, 2:05 p.m. EDT

Hi

if you are in 2D-axi, you should only see a rectangle = cut view of your cylinder. The results will be projected onto a 3D view (if you are in 4.2 or later)
In 2D-axi do not forget (see the doc):
1) work only in the Right I-IV quadrant (only for r>0 =horizontal axis >0) remove/cut all geometry left for the axis line r=0
2) volume is a area *2*pi*r and line is a surface *2*pi*r in integrations

--
Good luck
Ivar



Hello Lvar,

May I ask what is the volume for this case in 3D geometry please?
Thank you so much
[QUOTE] Hi if you are in 2D-axi, you should only see a rectangle = cut view of your cylinder. The results will be projected onto a 3D view (if you are in 4.2 or later) In 2D-axi do not forget (see the doc): 1) work only in the Right I-IV quadrant (only for r>0 =horizontal axis >0) remove/cut all geometry left for the axis line r=0 2) volume is a area *2*pi*r and line is a surface *2*pi*r in integrations -- Good luck Ivar [/QUOTE] Hello Lvar, May I ask what is the volume for this case in 3D geometry please? Thank you so much

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