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Combining Derived Values

Posted 22 mar 2023, 06:52 GMT-4 Version 6.0 3 Replies

Hendrik Mechanical Engineering
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I would like to use the result of a certain Derived Value in the calculation of another Derived value.

For my problem, I need to compute two surface integrations and figure out their ratio. I have done this by computing two derived values, and exporting the values to MATLAB.

Is there a way to directly do this in COMSOL? So finding a global evaluation as a function of other "derived values"?

3 Replies Last Post 23 mar 2023, 06:32 GMT-4
Gunnar Andersson COMSOL Employee

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Posted: 3 years ago 22 mar 2023, 08:39 GMT-4
Updated: 3 years ago 22 mar 2023, 08:39 GMT-4

You can do this using evaluation groups:

  • Create an evaluation group that contains two surface integrations.

  • The Transformation section in the evaluation group contains a Transformation type drop-down list. Choose General in the list. Set Expression to int1/int2 (the tags of the integration features).

  • Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations.

You can do this using evaluation groups: * Create an evaluation group that contains two surface integrations. * The **Transformation** section in the evaluation group contains a **Transformation type** drop-down list. Choose **General** in the list. Set **Expression** to int1/int2 (the tags of the integration features). * Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations.
Dave Greve
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Posted: 3 years ago 22 mar 2023, 11:56 GMT-4

You can do this using evaluation groups:

  • Create an evaluation group that contains two surface integrations.

  • The Transformation section in the evaluation group contains a Transformation type drop-down list. Choose General in the list. Set Expression to int1/int2 (the tags of the integration features).

  • Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations.

Interesting, I did not know about this. Learn something every day.

Another (more obscure) way to do this is to define two integration coupling variables, and do a global evaluation of the ratio.

>You can do this using evaluation groups: > >* Create an evaluation group that contains two surface integrations. > >* The **Transformation** section in the evaluation group contains a **Transformation type** drop-down list. Choose **General** in the list. Set **Expression** to int1/int2 (the tags of the integration features). > >* Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations. Interesting, I did not know about this. Learn something every day. Another (more obscure) way to do this is to define two integration coupling variables, and do a global evaluation of the ratio.
Hendrik Mechanical Engineering
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Posted: 3 years ago 23 mar 2023, 06:32 GMT-4

You can do this using evaluation groups:

  • Create an evaluation group that contains two surface integrations.

  • The Transformation section in the evaluation group contains a Transformation type drop-down list. Choose General in the list. Set Expression to int1/int2 (the tags of the integration features).

  • Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations.

Hello Gunnar,

Thanks for your helpful reply! It works like a charm.

>You can do this using evaluation groups: > >* Create an evaluation group that contains two surface integrations. > >* The **Transformation** section in the evaluation group contains a **Transformation type** drop-down list. Choose **General** in the list. Set **Expression** to int1/int2 (the tags of the integration features). > >* Evaluate: The result is the element-wise ratio between the integrals in the two surfaces integrations. Hello Gunnar, Thanks for your helpful reply! It works like a charm.

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