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use result from a study to calculate a variable and use this as input for another physics module

Posted May 24, 2019, 5:51 a.m. EDT RF & Microwave Engineering, Parameters, Variables, & Functions, Studies & Solvers Version 5.4 1 Reply

Rik Limpens
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Dear COMSOL users,

I'm a student and attempting a RF system in combination with a DC magnetic field.

First, I simulated the magnetic field of my model in COMSOL. Now in my next study (frequency domain, RF physics) I need to use the previously calculated magnetic field to calculate the permittivity matrix: I need to calculate the local cyclotronfrequency, which depends on the local magnetic field (mfnc.Bz).

Now my question is: How do I use my result from the local magnetic field study to calculate all local cyclotron frequency and use this as input for my permittivity matrix in the RF module?

Thanks in advance.

Kind regards, Rik

1 Reply Last Post May 25, 2019, 6:06 a.m. EDT
Alexis Prel
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Posted: 5 years ago May 25, 2019, 6:06 a.m. EDT

Hi Rik,

You should have a look at the documentation of the withsol operator, it is used in the following way:

withsol('sol_tag', expr)

This will evaluate expr using the results from the solution with tag sol_tag for the values of the dependent variables (such as mfnc.Bz in your case). If you start using parametric sweeps, you should look at the setval operators, among others, which helps you further select your solution source.

It is possible that you are not seeing the tag of your solution nodes. To make it visible, at the top of the model builder window click the little arrow on the right and tick the "Tag" checkbox.

Hi Rik, You should have a look at the documentation of the `withsol` operator, it is used in the following way: withsol('sol_tag', expr) This will evaluate `expr` using the results from the solution with tag `sol_tag` for the values of the dependent variables (such as `mfnc.Bz` in your case). If you start using parametric sweeps, you should look at the `setval` operators, among others, which helps you further select your solution source. It is possible that you are not seeing the tag of your solution nodes. To make it visible, at the top of the model builder window click the little arrow on the right and tick the "Tag" checkbox.

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