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Basic capacitance simulation: non physical variation of results with minor modification of mesh

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Hi all,

I am trying to simulate capacitance between two electrodes with the electrostatics module of Comsol 4.2a using a model succinctly described in the attached picture.

I want later to investigate the influence of a "trench" (rectangle R in the picture) in material 2, i.e. the rectangle R will have the properties of material 1.

Before doing this, I checked what happen when I insert the rectangle R in the model but still apply the properties of material 2 to it. And here comes the unphysical results: the predicted capacitance value vary (quite importantly) with the height d of the rectangle R. This does not make sense from a physical point of view . I understand that the mesh is modified each time that the value of d is changed and that this discrepancy may be related to that. But this is very annoying to me as I feel that I will not be able to make the difference between numerical artifacts and real capacitance variation when I will investigate the influence of trenches in material 2.

Any suggestion to solve this issue would be appreciated.

Thanks


2 Replies Last Post Apr 13, 2012, 10:27 a.m. EDT

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Posted: 1 decade ago Apr 13, 2012, 5:37 a.m. EDT
Hi Michael Renaud,
The answer is in your question, I think that maybe you will use Moving Mesh (ALE) application mode to make a frame to allow the mesh to move. Can you attach your model to take a look.


I understand that the mesh is modified each time that the value of d is changed and that this discrepancy may be related to that.


Hi Michael Renaud, The answer is in your question, I think that maybe you will use Moving Mesh (ALE) application mode to make a frame to allow the mesh to move. Can you attach your model to take a look. [QUOTE] I understand that the mesh is modified each time that the value of d is changed and that this discrepancy may be related to that. [/QUOTE]

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Posted: 1 decade ago Apr 13, 2012, 10:27 a.m. EDT
Thanks for your answer Amine.
I found the problem: what made the mess was just the "infinite" elements that I used in my model. If I replace them by large surface without the "infinite" property, I do not observe the problem mentioned before.
Thanks for your answer Amine. I found the problem: what made the mess was just the "infinite" elements that I used in my model. If I replace them by large surface without the "infinite" property, I do not observe the problem mentioned before.

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