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Units in Comsol

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Hello,

I have three problems with units in Comsol.

I am trying to simulate a MEMS device in Comsol. I prepared my 3D model in Inventor and I used "mm" as my unit. When I want to transfer my model to Comsol 4.1, before I transfer my model, should I change the unit to "mm" (when Comsol asks abut the unit) or should I just transfer it to Comsol and it realizes that the units are in "mm"? If I have to define it in Comsol that my units are in "mm", how about if I draw in "m" in Inventor, and transfer it to Comsol and define "mm" as the unit in Comsol. Would it work?

Since I am modeling a MEMS device, the dimensions are very small (MAX=100 um). When I draw my model in Inventor with "micro meter" as my unit, as soon as I transfer it to Comsol, when I want to define the material, I get an error, saying it has problems in Geometry. It seems that it is TOO SMALL. What should I do?


I really appreciate if anyone can guide me.

Thank you,

Sincerely,

Keivan

2 Replies Last Post 23.07.2011, 12:20 GMT-4

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Posted: 1 decade ago 22.07.2011, 08:29 GMT-4
I think you should set both units to be the same in each program. Once you import in the model, you can then check the dimensions with the measurement tool in the GUI and make sure they are what they should be.

Before adding the physics or materials, make sure your model meshes first. It might help you to sort out problems with domains if your exporting program is adding adding small faces or slivers to the geometry. If that is the case you will need to defeature.

I would also suggest that drawing it in COMSOL is a good idea as well. While a bit clunky, you can at least control the geometry better.
I think you should set both units to be the same in each program. Once you import in the model, you can then check the dimensions with the measurement tool in the GUI and make sure they are what they should be. Before adding the physics or materials, make sure your model meshes first. It might help you to sort out problems with domains if your exporting program is adding adding small faces or slivers to the geometry. If that is the case you will need to defeature. I would also suggest that drawing it in COMSOL is a good idea as well. While a bit clunky, you can at least control the geometry better.

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Posted: 1 decade ago 23.07.2011, 12:20 GMT-4
Thank you.....I think checking with the measurement tool is the best way......I am still having problems with errors, which I think are related to the meshing......The one that keep repeating says "Out of memory during assembly." I tried to use a bigger mesh size, but it did not work.....

Thank you again....

Keivan
Thank you.....I think checking with the measurement tool is the best way......I am still having problems with errors, which I think are related to the meshing......The one that keep repeating says "Out of memory during assembly." I tried to use a bigger mesh size, but it did not work..... Thank you again.... Keivan

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