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How to get variable at a domain/boundary

Posted Apr 11, 2023, 12:25 p.m. EDT General, Equation-Based Modeling Version 6.0 3 Replies

Junfeng Liang
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Hi, I am running a thermal simulation. The variable is T. I want to use the average of T at a surface as a parameter in a function f(average(T_surface)) as an input for a temperature boundary condition. Can I do that? If so , how may I get the local T and what is the syntax for average it?

Thank you.

3 Replies Last Post Apr 13, 2023, 2:47 a.m. EDT
Magnus Ringh COMSOL Employee

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Posted: 2 years ago Apr 12, 2023, 7:59 a.m. EDT

Hi Junfeng,

You can add an Average operator from the Definitions>Nonlocal Couplings menu. Then define it on the boundary (surface) where you want to compute the average. It will generate an operator with a name like aveop1. Use it somewhere in your model as aveop1(T) for the average temperature on that boundary.

Best regards,

Magnus

Hi Junfeng, You can add an **Average** operator from the **Definitions>Nonlocal Couplings** menu. Then define it on the boundary (surface) where you want to compute the average. It will generate an operator with a name like `aveop1`. Use it somewhere in your model as `aveop1(T)` for the average temperature on that boundary. Best regards, Magnus
Junfeng Liang
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Posted: 2 years ago Apr 12, 2023, 7:46 p.m. EDT

Thank you so much! What if I directly use boundary probe. Will that automatically give me the average?

I did something before your answer. I defined two boundary probes (T_c, T_h) on two surfaces for T and then put into a variable in terms of f (T_c, T_h). When I used f as my input, I only defined on one of the surface. It ran through, but I am not sure whether that is what I wanted or not.

Thank you so much! What if I directly use boundary probe. Will that automatically give me the average? I did something before your answer. I defined two boundary probes (T_c, T_h) on two surfaces for T and then put into a variable in terms of f (T_c, T_h). When I used f as my input, I only defined on one of the surface. It ran through, but I am not sure whether that is what I wanted or not.
Magnus Ringh COMSOL Employee

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Posted: 2 years ago Apr 13, 2023, 2:47 a.m. EDT

Hi Junfeng,

Yes, a boundary probe can be of an average type and would also work, but an average operator seems like a more flexible options. Probes are primarily intended for monitoring parts of the solution during a computation.

Best regards,

Magnus

Hi Junfeng, Yes, a boundary probe can be of an average type and would also work, but an average operator seems like a more flexible options. Probes are primarily intended for monitoring parts of the solution during a computation. Best regards, Magnus

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