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help for time dependent heat source

Posted Apr 11, 2012, 5:35 a.m. EDT Heat Transfer & Phase Change, Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.2, Version 4.2a 4 Replies

Joaquim Har
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hello,

I am a newbie in comsol things, however, have already ansys experience.

I am looking for a possibility of a physical time-dependent heat source (0-10s [0 W], 10-20s [1000 W], 20-1000s [0 W]) raise. I've seen in comsol there is a rectangular function, I could use this function. and how exactly?

is there a tutorial for such a case?

Thank you. jojo
4 Replies Last Post Apr 13, 2012, 8:01 a.m. EDT
Harmke van der Velde
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Posted: 1 decade ago Apr 11, 2012, 9:32 a.m. EDT
Maybe you can use a step function 2 times. The first up at 10 s and the second a step down at 20 s.
Than use this function in the boundary conditions.
Maybe you can use a step function 2 times. The first up at 10 s and the second a step down at 20 s. Than use this function in the boundary conditions.
Rahul Borhade
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Posted: 1 decade ago Apr 12, 2012, 1:56 a.m. EDT
you may try interpolation function, just right click on global definitions in model builder window then click on interpolation function, there you can specify any quantity varying with time.
you may try interpolation function, just right click on global definitions in model builder window then click on interpolation function, there you can specify any quantity varying with time.
Joaquim Har
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Posted: 1 decade ago Apr 13, 2012, 5:32 a.m. EDT
hello,

I myself have found a solution, I have a rectangular function and a parameter defined with the heat source and a time-dependent variable with the rectangular function, then I have to load the model heat source definition of the multiplikation of variable and parameter.

But I have a new question:

When I model at a certain point or surface temperature is reached a previously known, is an additional load to be applied, so to speak a kind of chain reaction.

sure someone has a tip?

Thank you. jojo
hello, I myself have found a solution, I have a rectangular function and a parameter defined with the heat source and a time-dependent variable with the rectangular function, then I have to load the model heat source definition of the multiplikation of variable and parameter. But I have a new question: When I model at a certain point or surface temperature is reached a previously known, is an additional load to be applied, so to speak a kind of chain reaction. sure someone has a tip? Thank you. jojo
Harmke van der Velde
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Posted: 1 decade ago Apr 13, 2012, 8:01 a.m. EDT
Maybe you can use a kind of control function.
An example of a PID control you can find here: www.comsol.com/showroom/gallery/866/

I'm not sure if this is what you are looking for.
Maybe you can use a kind of control function. An example of a PID control you can find here: http://www.comsol.com/showroom/gallery/866/ I'm not sure if this is what you are looking for.

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