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How to apply a complex eigenvalue
Posted 8 juil. 2010, 10:17 UTC−4 3 Replies
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Hi all,
I'm doing an application which involves complex eigenvalue. I have some global expression : y=f(real(lambda), imag(lambda)), y is added in a boundary condition, and I did damped eigenfrequency analysis, expected to have a complex eigenvalue, but errors came out as : undefined value found.
I'm stuck, so does anyone have experience with complex eigenvalue? How to apply this in comsol.
I'm doing an application which involves complex eigenvalue. I have some global expression : y=f(real(lambda), imag(lambda)), y is added in a boundary condition, and I did damped eigenfrequency analysis, expected to have a complex eigenvalue, but errors came out as : undefined value found.
I'm stuck, so does anyone have experience with complex eigenvalue? How to apply this in comsol.
3 Replies Last Post 12 juil. 2010, 04:51 UTC−4
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Posted:
1 decade ago
Hi
Normally COMNSOL is rather limited on accepting complex values or giving them back as such, in the sens that arrays are normally not accepted in the fields, only real scalars.
There are several exceptions, such as in RF for epsilon_r and n, k ... And for the results COMSOL uses often the "phasor" and the phase value to get hand on the imaginary part of a result. Then you must sometimes force the use of imaginary numbers, if COMSOL does not detect this itself.
Check the doc for your application mode/physics
Good luck
Ivar
Normally COMNSOL is rather limited on accepting complex values or giving them back as such, in the sens that arrays are normally not accepted in the fields, only real scalars.
There are several exceptions, such as in RF for epsilon_r and n, k ... And for the results COMSOL uses often the "phasor" and the phase value to get hand on the imaginary part of a result. Then you must sometimes force the use of imaginary numbers, if COMSOL does not detect this itself.
Check the doc for your application mode/physics
Good luck
Ivar
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Posted:
1 decade ago
Ivar, thank you again for your kindly reply. Hope there are more engineers like you, especially who belongs to comsol, to guide us newbies.
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Posted:
1 decade ago
Hi
To make it clear I'm NOT by COMSOL, I'm just a fan of the tool, and I do my personal COMSOL training by being active on the Forum, you learn a lot like that.
If you are a newbe, then I would strongly suggest that you get onto some of the COMSOL organised training courses, that really gives you a kick start. They cost a little (still cheaper that most of the competition tools, but pls do not tell COMSOL ;) but these are really good.
If you are part of a univeristy, propose to have the institution to organise a general COMSOL seminar, I'm sure they can find a way to make it cheaper for their students.
Finally, the only thing you need is enough time to go through the numerous examples and try it out on simple cases, before you complexify.
Have fun COMSOLING
Ivar
To make it clear I'm NOT by COMSOL, I'm just a fan of the tool, and I do my personal COMSOL training by being active on the Forum, you learn a lot like that.
If you are a newbe, then I would strongly suggest that you get onto some of the COMSOL organised training courses, that really gives you a kick start. They cost a little (still cheaper that most of the competition tools, but pls do not tell COMSOL ;) but these are really good.
If you are part of a univeristy, propose to have the institution to organise a general COMSOL seminar, I'm sure they can find a way to make it cheaper for their students.
Finally, the only thing you need is enough time to go through the numerous examples and try it out on simple cases, before you complexify.
Have fun COMSOLING
Ivar