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Interpolation function define in material list

Posted May 13, 2020, 3:02 p.m. EDT Low-Frequency Electromagnetics, Materials, Parameters, Variables, & Functions 3 Replies

Jun
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Hi,

I have read so many posts about this problem but still can't seem to find an answer:

I'm trying to define my permittivity as frequency dependent in my material. I have an interpolation function of a local table of values with t being frequency and f(t) my permittivity. My function name is defined as epsr_SIRB, the units for argument and function are Hz and 1 respectively. My problem is that I can't seem to define my argument as frequency anywhere??? I tried defining permittivity in my material as epsr_SIRB(t) but COMSOL doesn't seem to recognize it. If I only write epsr_SIRB, COMSOL gives out an error of unknown variable. So my question is: how do I define my argument in the table correctly? Or better yet, how do I define this function in my material table so the values will be read?

Would appreciate any help! Jun

3 Replies Last Post May 13, 2020, 6:33 p.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 5 years ago May 13, 2020, 3:45 p.m. EDT

Jun,

you can quickly make a little example. Make a new model with mf physics and import Water, liqid from the Materials library. The material definition has the speed of sound cs defined with an interpolation function. So if you add your table into an interpolation function epsr_SIRB(t) you can add it in the Basic properties as eps_SIRB(freq). Note that the variable t in the interpolation definition is only a generic variable, while freq is the independent frequency variable in frequency domain studies.

Hope this helps, Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Jun, you can quickly make a little example. Make a new model with mf physics and import Water, liqid from the Materials library. The material definition has the speed of sound cs defined with an interpolation function. So if you add your table into an interpolation function epsr_SIRB(t) you can add it in the Basic properties as eps_SIRB(freq). Note that the variable t in the interpolation definition is only a generic variable, while freq is the independent frequency variable in frequency domain studies. Hope this helps, Cheers Edgar
Jun
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Posted: 5 years ago May 13, 2020, 3:55 p.m. EDT

Hi Edgar,

thank you for your quick response! I guess I was too caught up in wanting to define it at the Interpolation settings and did not realize I could directly define it at the Basic part. It doesn't give me an error now, thanks! Have a good evening, Jun

Hi Edgar, thank you for your quick response! I guess I was too caught up in wanting to define it at the Interpolation settings and did not realize I could directly define it at the Basic part. It doesn't give me an error now, thanks! Have a good evening, Jun
Pu
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Posted: 5 years ago May 13, 2020, 6:33 p.m. EDT

Either way works. You for sure can define an interpolation function for the purpose.

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ZHANG, Pu
School of Physics,
Huazhong University of Science and Technology
Either way works. You for sure can define an interpolation function for the purpose.

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