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Change value of expression seperately for different domains

Posted 25 mars 2011, 10:45 UTC−4 Interfacing, Materials Version 4.1 4 Replies

Tanja Etzelstorfer
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Hi all!

I am quite new in Comsol 4.1 and have the following question:

I created a variable xGe with the geometric scope "Entire model" since I want to use it in every domain.
Now I'd like to give this variable a different expression depending on the domain (let's say be a constant in domain1 and a function in domain2).
Where can I set the value of the variable separately for different domains?

Thanks for the help in advance!
Tanja
4 Replies Last Post 25 mars 2011, 18:14 UTC−4
Xiaogai Li
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Posted: 1 decade ago 25 mars 2011, 10:57 UTC−4
Hi,

I think You can define different variables (under Model. Definitions) for each subdomain,
say "Variables 1", "Variables 2" ...., add different expressions you want.

Then for each variables, set the "Geometric entity level" from "Entire model" to "Domain", add the domain you want to the corresponding variables.
Hope it helps.

XLi
Hi, I think You can define different variables (under Model. Definitions) for each subdomain, say "Variables 1", "Variables 2" ...., add different expressions you want. Then for each variables, set the "Geometric entity level" from "Entire model" to "Domain", add the domain you want to the corresponding variables. Hope it helps. XLi
Tanja Etzelstorfer
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Posted: 1 decade ago 25 mars 2011, 11:06 UTC−4
Hi XLi!

Thanks for the answer. I know that, but that's not exactly what I want. I'd like to have just one variable which has a different value in the different domains, since I want to script models in Matlab independently of how many domains are in the model.

Tanja
Hi XLi! Thanks for the answer. I know that, but that's not exactly what I want. I'd like to have just one variable which has a different value in the different domains, since I want to script models in Matlab independently of how many domains are in the model. Tanja
Magnus Ringh COMSOL Employee

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Posted: 1 decade ago 25 mars 2011, 12:16 UTC−4
Hi,

Instead, use a Variables node for each domain with a manual selection including a single domain only and define a single variable with the same name in each but with a different value for its description. Then you have a single variable with different values in different domains. Not really sure that it fits your application but this works well in the COMSOL Multiphysics environment.

Best regards,
Magnus Ringh, COMSOL
Hi, Instead, use a Variables node for each domain with a manual selection including a single domain only and define a single variable with the same name in each but with a different value for its description. Then you have a single variable with different values in different domains. Not really sure that it fits your application but this works well in the COMSOL Multiphysics environment. Best regards, Magnus Ringh, COMSOL
Tanja Etzelstorfer
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Posted: 1 decade ago 25 mars 2011, 18:14 UTC−4
Hi Magnus!

Thanks for your help, that's exactly what I wanted. :)
There is now another issue.. If I update the variable in Comsol and then load the model in Matlab I have to load the model a few times until it contains the updated values. What could be the reason for that?

Best wishes,
Tanja
Hi Magnus! Thanks for your help, that's exactly what I wanted. :) There is now another issue.. If I update the variable in Comsol and then load the model in Matlab I have to load the model a few times until it contains the updated values. What could be the reason for that? Best wishes, Tanja

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