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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Math operations with different solutions

Posted 2012年9月5日 GMT-4 07:08 Heat Transfer & Phase Change, Results & Visualization Version 4.2 4 Replies

Antonio Lopez
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Hello. I hope someone can help me with this question.

Is it possible to operate with different post-processing solutions? For example, I want to obtain a ratio between a temperature field calculated with initial thermal parameters of the materials and the temperature field obtained with some parameters modified (with no changes in the geometry and the mesh). This way I want to obtain a surface plot to see where the temperature has decreased from the initial situation (ratio>1).

It seems this is not possible with Comsol, so I have tried to export both temperature fields to files (in spreadsheet and sectionwise formats) to operate them y Matlab, but these format don´t seem to be easy to use in Matlab.

Any suggestions, please?
Thanks in advance.
4 Replies Last Post 2012年9月6日 GMT-4 14:23
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2012年9月5日 GMT-4 15:11
Hi

You can compare results from 2 solution (data sets) based on the same model, and certainly on global results, but you need to define them in the "Definitions" node far up and either solve or at lest update your solution. Then you might use them for the postprocessing.

If you define them only in the potprocessing, you cannot access themm without exporting them to an external data file and process them there

--
Good luck
Ivar
Hi You can compare results from 2 solution (data sets) based on the same model, and certainly on global results, but you need to define them in the "Definitions" node far up and either solve or at lest update your solution. Then you might use them for the postprocessing. If you define them only in the potprocessing, you cannot access themm without exporting them to an external data file and process them there -- Good luck Ivar
Antonio Lopez
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Posted: 1 decade ago 2012年9月6日 GMT-4 04:17
Dear Ivar,

thank you for your help, but I´m not sure to understand you correctly.
In my model I have defined a variable "Tp" (which is actually the temperature in the whole model T) in the definitions node. Then I solve my model for a certain value of a thermal parameter. Then I change that parameter, I go to Study 1 and select "Show default solver" and then solve the problem again. Now I have two solutions (Solution 1 and Solution 3) in the data sets node. In this situation I can draw both surface plots with the variable "Tp" for Solution 1 and Solution 3, so I can compare them. But, is there a way to plot, for example, Tp(solution 1)/Tp(solution 3)?

Thank you again.
Dear Ivar, thank you for your help, but I´m not sure to understand you correctly. In my model I have defined a variable "Tp" (which is actually the temperature in the whole model T) in the definitions node. Then I solve my model for a certain value of a thermal parameter. Then I change that parameter, I go to Study 1 and select "Show default solver" and then solve the problem again. Now I have two solutions (Solution 1 and Solution 3) in the data sets node. In this situation I can draw both surface plots with the variable "Tp" for Solution 1 and Solution 3, so I can compare them. But, is there a way to plot, for example, Tp(solution 1)/Tp(solution 3)? Thank you again.
Jeff Hiller COMSOL Employee

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Posted: 1 decade ago 2012年9月6日 GMT-4 08:22
Hello Antonio,
You will need to use a Join dataset. This concept was introduced at version 4.2a, so you will need to update your software first.
Hello Antonio, You will need to use a Join dataset. This concept was introduced at version 4.2a, so you will need to update your software first.
Antonio Lopez
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Posted: 1 decade ago 2012年9月6日 GMT-4 14:23
Ok. Thank you very much for the information. I will update as soon as possible.
Ok. Thank you very much for the information. I will update as soon as possible.

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