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Assignment of material properties in each domain in General coefficient form PDE

Posted Oct 7, 2020, 7:20 a.m. EDT 1 Reply

Chironjeet Chaki
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Hi,

I build a model which includes 2 parts, each has a specific constant material property. For example, part/domain 1 has the absorptions coefficient a=50 and the other part/domain of the model will be a=100. Now I use the general coefficient form PDE and want to assign those absorptions coefficients in the PDE dialog. How can I do this?

Thank You, Chironjeet

1 Reply Last Post Oct 9, 2020, 6:49 a.m. EDT
Magnus Ringh COMSOL Employee

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Posted: 4 years ago Oct 9, 2020, 6:49 a.m. EDT

Hi,

There are some different ways to do this:

  1. You can add another Coefficent Form PDE node under the main Coefficent Form PDE interface node and assign it to the other domain and use the same values for the PDE coefficients except for the a coefficient.
  2. You can use the predefined dom variable that evaluates to the domain number. Enter a value like 50*(dom==1)+100*(dom==2), which will be evaluated to 50 in domain 1 and 100 in domain 2.
  3. Add two Variables nodes under Component>Definitions and define them as valid in domains, the first one in domain 1 and the second one in domain 2. In both Variables tables, add a variable with the same name and with the value of 50 for the one defined in domain 1 and 100 in the one defined in domain 2. Then enter that variable name as the value for a in the Coefficient Form PDE interface.

Best regards, Magnus Ringh

Hi, There are some different ways to do this: 1. You can add another **Coefficent Form PDE** node under the main **Coefficent Form PDE** interface node and assign it to the other domain and use the same values for the PDE coefficients except for the *a* coefficient. 2. You can use the predefined `dom` variable that evaluates to the domain number. Enter a value like `50*(dom==1)+100*(dom==2)`, which will be evaluated to 50 in domain 1 and 100 in domain 2. 3. Add two **Variables** nodes under **Component>Definitions** and define them as valid in domains, the first one in domain 1 and the second one in domain 2. In both **Variables** tables, add a variable with the same name and with the value of 50 for the one defined in domain 1 and 100 in the one defined in domain 2. Then enter that variable name as the value for *a* in the Coefficient Form PDE interface. Best regards, Magnus Ringh

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