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model the dielectric response of OIP insulation in frequency domain
Posted Jul 17, 2012, 7:24 p.m. EDT Materials Version 4.2a 2 Replies
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hello,
I am the freshman to COMSOL. I was trying to measure the dielectric response in frequency domain
which the permittivity is frequency dependent, I am wondering whether i can define the permittivity like this way:
esp = 2.2 - i*A/(B*2*pi*freq)
and where i can plug in this formula?
also i don't know if i wanna apply the sinusoidal voltage on a electrode. can i just define the voltage as 2*sin(2*pi*freq*t) in the "electrical potential" of the boundaries selection.
Thanks!
Sam
I am the freshman to COMSOL. I was trying to measure the dielectric response in frequency domain
which the permittivity is frequency dependent, I am wondering whether i can define the permittivity like this way:
esp = 2.2 - i*A/(B*2*pi*freq)
and where i can plug in this formula?
also i don't know if i wanna apply the sinusoidal voltage on a electrode. can i just define the voltage as 2*sin(2*pi*freq*t) in the "electrical potential" of the boundaries selection.
Thanks!
Sam
2 Replies Last Post Jul 18, 2012, 5:01 p.m. EDT
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Posted:
1 decade ago
Hi
If you have defined "freq" somewhere, or are using a frequency domain solver that should work, for eps but call it something else than eps, as that is already an internal variable of COMSOL (the smallest value that can be distinguished from 1 on your floating point CPU)
select the physics domain node for the particular material and use an user defined dielectric constant with this equation.
you can also apply a sinus law and solve in transient / time stepping as you describe, but this will take long to solve and often you get many transient at the beginning as mostly the initial conditions are far from "steady state" level, to improve this ,sometimes its worth to start with a stationary case to put the variables ina logic state and then start a time series from there with the previously solved initial values.
Anyhow, if you have a steady state sinus excitation applied, then it is worth to consider the harmonic devcelopment and use a frequency domain solver, check the COSMOl doc
--
Good luck
Ivar
If you have defined "freq" somewhere, or are using a frequency domain solver that should work, for eps but call it something else than eps, as that is already an internal variable of COMSOL (the smallest value that can be distinguished from 1 on your floating point CPU)
select the physics domain node for the particular material and use an user defined dielectric constant with this equation.
you can also apply a sinus law and solve in transient / time stepping as you describe, but this will take long to solve and often you get many transient at the beginning as mostly the initial conditions are far from "steady state" level, to improve this ,sometimes its worth to start with a stationary case to put the variables ina logic state and then start a time series from there with the previously solved initial values.
Anyhow, if you have a steady state sinus excitation applied, then it is worth to consider the harmonic devcelopment and use a frequency domain solver, check the COSMOl doc
--
Good luck
Ivar
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Posted:
1 decade ago
Thank you! Ivar.