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How to plot the "total stored energy" in BAW device

Posted 15.04.2011, 11:52 GMT-4 Version 4.1 3 Replies

Chi-Jung Cheng
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Hi,

I am trying to obtain the Q_factor for my BAW device. Based on the tutorial, the Q_factor of the device is obtained from two parameters, total power dissipation (Q_tot) and total stored energy (W_tot) and the equation will be

Q_factor= angular frequency * W_tot / Q_tot


After simulation, I can obtain and plot the angular frequency and Q_tot, however I couldn't obtain the W_tot.
Does anyone know how to obtain W_tot in piezoelectric Device.

Thanks
3 Replies Last Post 21.04.2011, 16:56 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 15.04.2011, 15:39 GMT-4
Hi

COMSOL gives you mostly densities (or values per element) that you must integrate over the volume or the voundaries where they apply. that is the easiest way to get to the "total" values.

in V4 define an operator on the correct Entity(ies), then define a global variable based on the applicatio of the operatoron the COMSOL evaluated (power/energy/current ...) density. then you can refer to this global value at will, in equations or as postprocessing items

--
Good luck
Ivar
Hi COMSOL gives you mostly densities (or values per element) that you must integrate over the volume or the voundaries where they apply. that is the easiest way to get to the "total" values. in V4 define an operator on the correct Entity(ies), then define a global variable based on the applicatio of the operatoron the COMSOL evaluated (power/energy/current ...) density. then you can refer to this global value at will, in equations or as postprocessing items -- Good luck Ivar
Chi-Jung Cheng
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Posted: 1 decade ago 21.04.2011, 15:45 GMT-4
Hi Ivar,

Thanks for your answer. I still have an question. Is that possible to plot total stored energy (W_tot) in the frequency domain? I can obtain total dissipation power but W_tot. Every time I try to plot, it just show error.
I was wondering if there any other way to obtain total stored energy of a device.

Thanks
Hi Ivar, Thanks for your answer. I still have an question. Is that possible to plot total stored energy (W_tot) in the frequency domain? I can obtain total dissipation power but W_tot. Every time I try to plot, it just show error. I was wondering if there any other way to obtain total stored energy of a device. Thanks
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 21.04.2011, 16:56 GMT-4
Hi

in the case of frequency sweep solver, most variables are given in "average" and rms values, the names are slightly changed, but they should appear in the lists (often _ave in suffix)

--
Good luck
Ivar
Hi in the case of frequency sweep solver, most variables are given in "average" and rms values, the names are slightly changed, but they should appear in the lists (often _ave in suffix) -- Good luck Ivar

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