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Extracting absorbed power

Posted Nov 12, 2012, 1:09 p.m. EST Results & Visualization 5 Replies

Benoit Queney
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Hi all!
I am currently doing a 2D model where I have an incoming power, and then I have absorption within the material.
As a result, I have the value of the intensity everywhere, but I don't know how to extract the amount of power that has been dissipated.
Would you have any idea?
Thank you very much,
Benoit
5 Replies Last Post Nov 20, 2012, 2:28 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 14, 2012, 1:38 a.m. EST
Hi

if you look carefully at the units, COMSOL results are motly in "denisties" or energy per meter^3 so you need to integrate these values over the "Domains" to get the total values out

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Good luck
Ivar
Hi if you look carefully at the units, COMSOL results are motly in "denisties" or energy per meter^3 so you need to integrate these values over the "Domains" to get the total values out -- Good luck Ivar
Benoit Queney
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Posted: 1 decade ago Nov 14, 2012, 6:35 a.m. EST
The problem is that if I integrate the power remaining on the whole domain, the result does not mean anything.
I want to the dissipated power, which is the problem. If I had it on all points, it would be easy to integrate.

What I am doing right now is to integrate the second derive of the absolute value of the intensity, (abs(Ixy)), but even after refining the meshing, the result is not satisfying (1W in gives 3W dissipated...)

Any idea?
The problem is that if I integrate the power remaining on the whole domain, the result does not mean anything. I want to the dissipated power, which is the problem. If I had it on all points, it would be easy to integrate. What I am doing right now is to integrate the second derive of the absolute value of the intensity, (abs(Ixy)), but even after refining the meshing, the result is not satisfying (1W in gives 3W dissipated...) Any idea?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 14, 2012, 2:23 p.m. EST
Hi

check your variables, and be sure you integrate the correct one, the doc describes also the different naming convention (at least now in 4.3a)

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Good luck
Ivar
Hi check your variables, and be sure you integrate the correct one, the doc describes also the different naming convention (at least now in 4.3a) -- Good luck Ivar
Benoit Queney
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Posted: 1 decade ago Nov 19, 2012, 10:27 a.m. EST
Hi Ivar,
I've been looking desperately for this naming, and I can not find it.
Do you know which it would be (for ex what kind of expression shoul I write to get this absorbed power?)

Thank you very much for your time.
Hi Ivar, I've been looking desperately for this naming, and I can not find it. Do you know which it would be (for ex what kind of expression shoul I write to get this absorbed power?) Thank you very much for your time.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 20, 2012, 2:28 a.m. EST
Hi

you are right I have forgotten about pure math mode, haven't been in there for some time ;)

But what disturbs me is the units. Are you really thinking 2D with 3D representation and per "meter" Z depth here ?

flux remain intensity/surface even in 2D you must "just" multiply implicitly by 1[m] in depth
And fixing an absolute value on a boundary means intensity/length times implicitly the depth of 1[m]

Take a closer look at the default HT case of COMSOL

Another point I would have chosen 2D-axi closer to your case I believe, but then you must not forget the loop length 2*pi*r here and there. now in 2D soul should just not forget to normalise for the depth, less than 1 cm at most I believe

So as you do it integrate "I" over the surface * 1[m] depth should give you the total value in the correct units, here its not the case the way I understand it.

I'm not sure of my comments, but it means one need to take more care with the units and that it's not easy to understand a model in this way, but it's a good exercise I agree, I just do not have enough time now to get into it
Sorry cant do better

--
Good luck
Ivar
Hi you are right I have forgotten about pure math mode, haven't been in there for some time ;) But what disturbs me is the units. Are you really thinking 2D with 3D representation and per "meter" Z depth here ? flux remain intensity/surface even in 2D you must "just" multiply implicitly by 1[m] in depth And fixing an absolute value on a boundary means intensity/length times implicitly the depth of 1[m] Take a closer look at the default HT case of COMSOL Another point I would have chosen 2D-axi closer to your case I believe, but then you must not forget the loop length 2*pi*r here and there. now in 2D soul should just not forget to normalise for the depth, less than 1 cm at most I believe So as you do it integrate "I" over the surface * 1[m] depth should give you the total value in the correct units, here its not the case the way I understand it. I'm not sure of my comments, but it means one need to take more care with the units and that it's not easy to understand a model in this way, but it's a good exercise I agree, I just do not have enough time now to get into it Sorry cant do better -- Good luck Ivar

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