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Output temperature data of a single point only,not the whole 3D field

Posted 26 ago 2016, 23:16 GMT-4 Heat Transfer & Phase Change, Results & Visualization Version 5.1 5 Replies

Zhichao Jia
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Hello ,
I have a large 3D model, the output is always beyond 10G. So I want to save temperature data of a single point only. Help document mentions little about this .
5 Replies Last Post 5 set 2016, 02:09 GMT-4
Magnus Ringh COMSOL Employee

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Posted: 8 years ago 29 ago 2016, 07:25 GMT-4
Hi,

You can do it by clearing the "Store in output" check box for the 3D temperature field in its Field node's settings window (probably called Temperature, under Solver Configurations>Solution>Dependent Variables). Then add an Integration coupling operator (typically called "intop1") at the point where you want to output the temperature data. You also need to add a Global ODEs and DAEs interface to create a new single degree of freedom (variable) for the temperature in that point. In the Global Equations node, define a name for that variable ("temp_in_point", for example) and then use

intop1(T)-temp_in_point

as the algebraic equation expression. COMSOL Multiphysics sets that expression to zero, so the equation becomes temp_in_point = intop1(T), which is the temperature at that point since an integration of a value at a point is the value itself.

You can then evaluate temp_in_point using a Global Evaluation node under Derived Values or as Global graph plot under a 1D Plot Group.

Best regards,
Magnus Ringh, COMSOL


Hi, You can do it by clearing the "Store in output" check box for the 3D temperature field in its Field node's settings window (probably called Temperature, under Solver Configurations>Solution>Dependent Variables). Then add an Integration coupling operator (typically called "intop1") at the point where you want to output the temperature data. You also need to add a Global ODEs and DAEs interface to create a new single degree of freedom (variable) for the temperature in that point. In the Global Equations node, define a name for that variable ("temp_in_point", for example) and then use intop1(T)-temp_in_point as the algebraic equation expression. COMSOL Multiphysics sets that expression to zero, so the equation becomes temp_in_point = intop1(T), which is the temperature at that point since an integration of a value at a point is the value itself. You can then evaluate temp_in_point using a Global Evaluation node under Derived Values or as Global graph plot under a 1D Plot Group. Best regards, Magnus Ringh, COMSOL
Zhichao Jia
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Posted: 8 years ago 29 ago 2016, 22:44 GMT-4

Thank you very much for your reply!
Now I have master the skill. If I want to save the data of line or surface, what should I do? Is model coupling a right choose?
Best regards,
Zhichao Jia
Thank you very much for your reply! Now I have master the skill. If I want to save the data of line or surface, what should I do? Is model coupling a right choose? Best regards, Zhichao Jia
Magnus Ringh COMSOL Employee

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Posted: 8 years ago 30 ago 2016, 11:04 GMT-4
Hi,

You should be able to use the same technique, but with a Boundary ODEs and DAEs interface instead (for the solution on a line in 2D, for example). In the latest versions of COMSOL Multiphysics (5.2 and 5.2a), you can also create a selection for a line, for example, and then restrict the output to only that selection (in the Values of Dependent Variables section of the study step node's Settings window). That is an easier and more straightforward method that does not require the addition of an extra algebraic equation.

Best regards,
Magnus Ringh, COMSOL
Hi, You should be able to use the same technique, but with a Boundary ODEs and DAEs interface instead (for the solution on a line in 2D, for example). In the latest versions of COMSOL Multiphysics (5.2 and 5.2a), you can also create a selection for a line, for example, and then restrict the output to only that selection (in the Values of Dependent Variables section of the study step node's Settings window). That is an easier and more straightforward method that does not require the addition of an extra algebraic equation. Best regards, Magnus Ringh, COMSOL
Zhichao Jia
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Posted: 8 years ago 4 set 2016, 08:09 GMT-4
Thank you very much for your help!

Best Regards!
Zhichao Jia
Thank you very much for your help! Best Regards! Zhichao Jia
Magnus Ringh COMSOL Employee

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Posted: 8 years ago 5 set 2016, 02:09 GMT-4
Hi,

You're welcome.

This blog post shows how to use these methods with some more detailed information:

www.comsol.com/blogs/minimize-your-model-file-size-with-storing-solution-techniques/

Best regards,
Magnus Ringh, COMSOL
Hi, You're welcome. This blog post shows how to use these methods with some more detailed information: https://www.comsol.com/blogs/minimize-your-model-file-size-with-storing-solution-techniques/ Best regards, Magnus Ringh, COMSOL

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