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What material is present by default in a hollow space?

Posted 27 apr 2018, 04:09 GMT-4 Structural & Acoustics, MEMS & Piezoelectric Devices, Structural Mechanics Version 4.3a 2 Replies

Vineeth Raj S
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Assume that I have a large acrylic block. Now, I machine a small circle in the center upto half way in the acrylic. Then I place an eleastic membrane on top of the acrylic such that the hole inside is filled with air.

When I try to model this, I m not able to specify air in the hollow place as it is not considered to be a domain. How can I model this? Does comsol assume air to be present in the hollow space by default or a vacuum or what??

Thank you.

2 Replies Last Post 11 mag 2018, 02:20 GMT-4
Louis Haeberle
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Posted: 7 years ago 1 mag 2018, 14:25 GMT-4

If that empty space is not a domain, COMSOL does not consider it at all in the model; no material is assigned to it, and it will not be meshed. You need to actually make a domain in the geometry and set the material as air.

This is also important if you have two objects in space and you want to calculate their interaction (via electric or magnetic fields for example), you need to make an air domain in the geometry that surrounds the two objects. If you don't, comsol will solve the model in the objects, but not in the space between them, yielding unphysical results.

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-- Louis Haeberle
MSc Student (Physics)
Silicon Spintronics Research Group (Pr. Pioro-Ladrière)
Université de Sherbrooke
If that empty space is not a domain, COMSOL does not consider it at all in the model; no material is assigned to it, and it will not be meshed. You need to actually make a domain in the geometry and set the material as air. This is also important if you have two objects in space and you want to calculate their interaction (via electric or magnetic fields for example), you need to make an air domain in the geometry that surrounds the two objects. If you don't, comsol will solve the model in the objects, but not in the space between them, yielding unphysical results.
Vineeth Raj S
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Posted: 7 years ago 11 mag 2018, 02:20 GMT-4

How to set the empty space as a domain?

How to set the empty space as a domain?

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