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Graphics in comsol

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Dear all,

I have drawn a nano size circle(say 15 nm) in 2D domain and I have taken that in to the 3D domain. Then I have drawn a cylinder of 15 micrometer to represent my boundary.( So the ratio is 15e-9 m/15e-6=1e-3). However When I see the boundary mode my circle is not show up as a circle but instead it appearing as a square. I would be greatfull if somebody explain me reason for this.

Manjula

3 Replies Last Post 2010年6月24日 GMT-4 11:58
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年6月24日 GMT-4 07:26
Hi

there are a few things to consider (and that I believe differs somewhat between 3.5 d 4) you have the relative sizes and absolute sizes and where are the references set to the relative sizes ?. And finally you have the graphical rendering resolution.

If in 3.5 your basic reference is 1[m] and the absolute resolution by default some 10um, relative values at 1E-5 and importing resolution at 10um (not the same as theabsolute resolution one) anything smaller will be simply supressed. So these values must be adapted if you work with smaller features (in thh preferences, and in the options of the file import)

In 4 you can define that your reference dimension is rather mm or even nm, rather than m, so any relative resolutionswill scale, but the import resolution (one of the hidden tabs of your file import) should be checked to ensure full import resolution, when working with small features.

Finally there are some resolution / number of segments per cercle in the graphics rendering, this is only the way small features are shown on the scree, the underlaying geoemtry is known as a sphere. You can take this as a similarity to the mesh size, meshing a circle witha gross pitch, ends up as a cube, in the worst case.

I assume its the last case you are interfering with, related to the ratio between the two spheres and their absolute small scale, There should be some settings in the 3.4 view tab to test, but I have not really be en plying with these so I'm not sure what to advise. So long your geometry is defined as a circle it should not affect the meshing, that anyhow transform your circle to a polygone, but with some nodes fixed on the boundary.

Hope this helps
Good luck
Ivar
Hi there are a few things to consider (and that I believe differs somewhat between 3.5 d 4) you have the relative sizes and absolute sizes and where are the references set to the relative sizes ?. And finally you have the graphical rendering resolution. If in 3.5 your basic reference is 1[m] and the absolute resolution by default some 10um, relative values at 1E-5 and importing resolution at 10um (not the same as theabsolute resolution one) anything smaller will be simply supressed. So these values must be adapted if you work with smaller features (in thh preferences, and in the options of the file import) In 4 you can define that your reference dimension is rather mm or even nm, rather than m, so any relative resolutionswill scale, but the import resolution (one of the hidden tabs of your file import) should be checked to ensure full import resolution, when working with small features. Finally there are some resolution / number of segments per cercle in the graphics rendering, this is only the way small features are shown on the scree, the underlaying geoemtry is known as a sphere. You can take this as a similarity to the mesh size, meshing a circle witha gross pitch, ends up as a cube, in the worst case. I assume its the last case you are interfering with, related to the ratio between the two spheres and their absolute small scale, There should be some settings in the 3.4 view tab to test, but I have not really be en plying with these so I'm not sure what to advise. So long your geometry is defined as a circle it should not affect the meshing, that anyhow transform your circle to a polygone, but with some nodes fixed on the boundary. Hope this helps Good luck Ivar

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Posted: 1 decade ago 2010年6月24日 GMT-4 11:48
Dear Ivar,

Thank you for your explanation. I am having both comsol 3.5 a and comsol 4.0. I need little more information. Is it better If I use 4.0 for my modeling to avoid my troubles I have indicated previously?. The other question is that I was unable to import 2D file to 3D in 4.0. It gave me an error. Is it impossible or Is there a special way to do that? Please be kind enough to give me a answer.

Thanks again.

manjula
Dear Ivar, Thank you for your explanation. I am having both comsol 3.5 a and comsol 4.0. I need little more information. Is it better If I use 4.0 for my modeling to avoid my troubles I have indicated previously?. The other question is that I was unable to import 2D file to 3D in 4.0. It gave me an error. Is it impossible or Is there a special way to do that? Please be kind enough to give me a answer. Thanks again. manjula

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年6月24日 GMT-4 11:58
Hi

current V4 is somewhat limited as not everything is in yet, V4.0a is around the corner, hope it will be better. I'm not using V4 really for my clients, to early, will see with V4.0a. but it's worth to learn quickly V4 as tehre are many ewn features and appoaches, and globally I set up and run amodel even quicker in V4, but I need still about the same (too long) time to document it fully.

For your 2D 3D, you can also in V4 import a 2D (define a 3D model, in geoemtry define a workplane and under the workplane tree define an import 2D sketch or build it up. Then extrude or revolve it into 3D (you cannot yet extrude or revolve meshes in V4, but I hope this will come)

Have fun Comsoling
Ivar
Hi current V4 is somewhat limited as not everything is in yet, V4.0a is around the corner, hope it will be better. I'm not using V4 really for my clients, to early, will see with V4.0a. but it's worth to learn quickly V4 as tehre are many ewn features and appoaches, and globally I set up and run amodel even quicker in V4, but I need still about the same (too long) time to document it fully. For your 2D 3D, you can also in V4 import a 2D (define a 3D model, in geoemtry define a workplane and under the workplane tree define an import 2D sketch or build it up. Then extrude or revolve it into 3D (you cannot yet extrude or revolve meshes in V4, but I hope this will come) Have fun Comsoling Ivar

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