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Plasmonic Wire Grating Not Working

Posted 21 nov 2011, 23:00 GMT-5 RF & Microwave Engineering, Parameters, Variables, & Functions Version 4.2, Version 4.3 3 Replies

A. Shoji Hall
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I followed the steps in the plasmonic wire grating tutorial for COMSOL 4.2. When I try to compute the results it says it has encountered a problem with stationary solver 1(sol1/s1) and Failed to evaluate variable jacobian. I took a look at my variable files and comsol says that emw.k0 is an unknown variable. The tutorial says to use this variable to define ka. How do i get comsol to recognize what emw.k0 is. Also what is emw.k0, the tutorial didn't explain what it was.
3 Replies Last Post 7 ago 2015, 01:26 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 22 nov 2011, 01:40 GMT-5
Hi

when you have a doubt about a variable (especially the COMSOL internals) the most interesting is to take a look on the "equation view" of COMSOL (turn on in the preferences or in the view icon of the model builder top border. Now I took a look and could find it in there, but the variables are not ordered so it is easy to miss something in the long list.
2nd place to look is in the Results - Derived values - Global Evaluation and - Integration evaluation. here you find the list of the post processing variables you may analyse. here you find "wave number in free space" which corresponds to the "k0" you see in the Wave Equation Electric - Equation view

The Jacobian error message is indicating that the solver cannot estimate a derivative of your case to find where to throw next solver varianle value. This mostly comes from the user having referred to a Boolean operation, a min(), max(), abs() ... operator value that are not derivable, or what I find mostly with this error a typo somewhere in the model ;)

take a second look, its not an "easy" model, but very illustrative

--
Good luck
Ivar
Hi when you have a doubt about a variable (especially the COMSOL internals) the most interesting is to take a look on the "equation view" of COMSOL (turn on in the preferences or in the view icon of the model builder top border. Now I took a look and could find it in there, but the variables are not ordered so it is easy to miss something in the long list. 2nd place to look is in the Results - Derived values - Global Evaluation and - Integration evaluation. here you find the list of the post processing variables you may analyse. here you find "wave number in free space" which corresponds to the "k0" you see in the Wave Equation Electric - Equation view The Jacobian error message is indicating that the solver cannot estimate a derivative of your case to find where to throw next solver varianle value. This mostly comes from the user having referred to a Boolean operation, a min(), max(), abs() ... operator value that are not derivable, or what I find mostly with this error a typo somewhere in the model ;) take a second look, its not an "easy" model, but very illustrative -- Good luck Ivar
Shashank Sarbada
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Posted: 1 decade ago 14 mag 2015, 01:39 GMT-4
I am facing the same problem that you mentioned although I am using 4.3. Did you find a way to fix it?
Since the expression emw.k0 is in orange, the issue is with units. How is this fixed?

Thank you
I am facing the same problem that you mentioned although I am using 4.3. Did you find a way to fix it? Since the expression emw.k0 is in orange, the issue is with units. How is this fixed? Thank you
Hasan Abbas
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Posted: 1 decade ago 7 ago 2015, 01:26 GMT-4
If you were following the FSS tutorial, the variables should have been as emw2.k0 rather than emw.k0.
If you were following the FSS tutorial, the variables should have been as emw2.k0 rather than emw.k0.

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