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Microwave heating model with multiple frequencies

Posted Apr 28, 2013, 5:44 p.m. EDT RF & Microwave Engineering, Heat Transfer & Phase Change, Modeling Tools & Definitions, Parameters, Variables, & Functions 4 Replies

Duarte Albuquerque
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Hi,

With the Microwave heating model, with a frequency-transient study is possible to simulate multiple frequencies in a well defined bandwidth? I have a input wave with a fixed bandwidth defined by a square function or a gaussian pdf.

I could do this with a time domain study, with the transient electromagnetic wave model. Bit if it is possible with the microwave heating model, this will be more apreciated.

Thanks in advance.
4 Replies Last Post Nov 27, 2013, 11:18 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 Apr 29, 2013, 2:25 a.m. EDT
Hi

normally you solve per frequency (so you do a spectrum analyser type scan over the frequency) but if you have a given bandwidth you need to integrate the energy over the bandwidth and use that as total generated or absorbed energy. This is not done automatically ba COMSOL, so you must define it. One way is to scan over a frequency domain, to get the frequency response and then correlate with your banndwidth, assuming indepedent linear rlations, and then get the resulting power value to use as a heat source for thermal analysis.
If your HT and RF are coupbled, then you must use a segregateds solver (perhaps still try a direct one) else you can do it in several separate solver steps

--
Good luck
Ivar
Hi normally you solve per frequency (so you do a spectrum analyser type scan over the frequency) but if you have a given bandwidth you need to integrate the energy over the bandwidth and use that as total generated or absorbed energy. This is not done automatically ba COMSOL, so you must define it. One way is to scan over a frequency domain, to get the frequency response and then correlate with your banndwidth, assuming indepedent linear rlations, and then get the resulting power value to use as a heat source for thermal analysis. If your HT and RF are coupbled, then you must use a segregateds solver (perhaps still try a direct one) else you can do it in several separate solver steps -- Good luck Ivar
Duarte Albuquerque
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Posted: 1 decade ago Apr 29, 2013, 7:10 a.m. EDT
Hi Ivan,

Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling?

First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures.

Kind Regards,

Duarte Albuquerque
Hi Ivan, Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling? First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures. Kind Regards, Duarte Albuquerque
Sohan Birla
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Posted: 1 decade ago Nov 27, 2013, 11:16 a.m. EST

Hi Ivan,

Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling?

First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures.

Kind Regards,

Duarte Albuquerque


Duarte,
I have tried running the RF modlule in frequency domain with a discrete frequencies and took a weighted average of power dissipation densities. The wighted avarge function depends on your magnetron bandwidth and type of spectrum . In heat transfer module simple use the weighted average heat source. For doing all this you will need MATALB livelink as COMSOL with operator does not work...

With best,
Sohan
[QUOTE] Hi Ivan, Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling? First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures. Kind Regards, Duarte Albuquerque [/QUOTE] Duarte, I have tried running the RF modlule in frequency domain with a discrete frequencies and took a weighted average of power dissipation densities. The wighted avarge function depends on your magnetron bandwidth and type of spectrum . In heat transfer module simple use the weighted average heat source. For doing all this you will need MATALB livelink as COMSOL with operator does not work... With best, Sohan
Sohan Birla
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Posted: 1 decade ago Nov 27, 2013, 11:18 a.m. EST

Hi Ivan,

Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling?

First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures.

Kind Regards,

Duarte Albuquerque


[QUOTE] Hi Ivan, Thanks for the Idea. I will try to integrate the frequency bandwith in each step of time domain simulation of the heating module. Do you think I should save the thermal source term in a table or use a global function for the thermal microwave coupling? First I will try just to integrate the frequency-domain simulation because I have a estimation of the source power for different initial temperatures. Kind Regards, Duarte Albuquerque [/QUOTE]

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