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Mesh of very thin geometries

Posted 14 mai 2014, 21:29 UTC−4 Mesh Version 4.3b 7 Replies

Xavier Rojas
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Hi,

I would like to study in a very thin geometry. It is basically a disk (diameter 5mm, thickness 1um) with 4 rectangular channels (width 1mm, thickness 1um). I understand that cannot use the automatic mesh for this geometry because of the large aspect ratio (~ 1000).

I have been reading other posts on this forum and I understand that I should use a Swept Mesh. I can easily do it for just a thin disk where source face and destination face are the two opposite faces of the disk. Unfortunately, I have a problem when I try with my geometry (disk and 4 channels). It works for the channels but It gives me the following error on the lateral face of the disk:

"Unsupported topology of linking face."

In order to work on the mesh, I have volontarly increase the thickness (disk and channels) to 1mm. Screenshots of the geometry and the error message are attached. I couldn't attache the .mph file because its size is too large (10M).

Could you help me with that problem?

Thanks
7 Replies Last Post 31 juil. 2014, 21:15 UTC−4
Lasse Murtomäki
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Posted: 1 decade ago 15 mai 2014, 08:36 UTC−4
Hi

How about this? I made a work plane where I drew the shape, made a union, keeping interior boundaries, and extruded it 1 µm. Now swept mesh is no problem.

Attached a screen shot and the model file. Wish you have 4.4 so you could open it.

BR
Lasse
Hi How about this? I made a work plane where I drew the shape, made a union, keeping interior boundaries, and extruded it 1 µm. Now swept mesh is no problem. Attached a screen shot and the model file. Wish you have 4.4 so you could open it. BR Lasse

Attachments:

Xavier Rojas
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Posted: 1 decade ago 15 mai 2014, 12:52 UTC−4
Hi,

Thank Lasse for your help. I don't have 4.4 yet but I will get it soon. I can see that it works well from your screenshot. However, I should have been more precise in the description because it turns out that the 4 channels are not (1mm x 1um) but (1mm x 0.5 um). The other thing is that 2 opposite channels must be extruded from the bottom plane and the 2 other channels from the top plane.

With this geometry, the disk has a different face on the bottom plane than on the top. To make a test I have just draw 1 disk and 2 channels using work planes. Then, I have used "form a composite domain" for the disk and the piece of channel inside the disk. I have tried to mesh the disk (see screen shot attached) but it does not work.

Do you have any idea how I could solve this problem?

Thanks a lot.
Hi, Thank Lasse for your help. I don't have 4.4 yet but I will get it soon. I can see that it works well from your screenshot. However, I should have been more precise in the description because it turns out that the 4 channels are not (1mm x 1um) but (1mm x 0.5 um). The other thing is that 2 opposite channels must be extruded from the bottom plane and the 2 other channels from the top plane. With this geometry, the disk has a different face on the bottom plane than on the top. To make a test I have just draw 1 disk and 2 channels using work planes. Then, I have used "form a composite domain" for the disk and the piece of channel inside the disk. I have tried to mesh the disk (see screen shot attached) but it does not work. Do you have any idea how I could solve this problem? Thanks a lot.

Attachments:

Lasse Murtomäki
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Posted: 1 decade ago 16 mai 2014, 04:13 UTC−4
Hi

I tried several things but was not able to find a solution. I wish somebody from Comsol support would reply this.

Lasse
Hi I tried several things but was not able to find a solution. I wish somebody from Comsol support would reply this. Lasse
Jeff Hiller COMSOL Employee

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Posted: 1 decade ago 16 mai 2014, 14:42 UTC−4
Hi Xavier,
If your license is eligible for support from COMSOL, feel free to contact our support team through support@comsol.com for assistance with this question.
Best,
Jeff
Hi Xavier, If your license is eligible for support from COMSOL, feel free to contact our support team through support@comsol.com for assistance with this question. Best, Jeff
Xavier Rojas
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Posted: 1 decade ago 16 mai 2014, 21:04 UTC−4
Hi Jeff,

Our COMSOL licence is provided by CMC Microsystems and I could not register it on COMSOL website. Do you know if it is possible to do it?

Thanks,
Xavier
Hi Jeff, Our COMSOL licence is provided by CMC Microsystems and I could not register it on COMSOL website. Do you know if it is possible to do it? Thanks, Xavier
Jeff Hiller COMSOL Employee

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Posted: 1 decade ago 19 mai 2014, 09:13 UTC−4
Yes.
Yes.

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Scott Rauscher
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Posted: 1 decade ago 31 juil. 2014, 21:15 UTC−4
Can you elaborate on how you did this, Jeff? This is exactly what I am trying to do.

Modeling a membrane 2µm thick over a suspended structure 20µm thick with different geometry for a MEMS application.

Thank you in advance for any help.
Can you elaborate on how you did this, Jeff? This is exactly what I am trying to do. Modeling a membrane 2µm thick over a suspended structure 20µm thick with different geometry for a MEMS application. Thank you in advance for any help.

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