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How to calculate the eigenfrequency and eigenmodes of a solid structure with fluids inside?
Posted Dec 16, 2009, 11:05 p.m. EST 1 Reply
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I know the solid structure can be calculated by using the structure mechanics module and the fluid structure can be calculated by using the acoustics module. But how to couple the two modules and obtain the coupled eigenfrequency as well as eigenmode? Can anyone give some brief explanation or a small example?
Thanks a lot!
Thanks a lot!
1 Reply Last Post Dec 26, 2009, 12:03 a.m. EST
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Posted:
1 decade ago
I would try to build a driven frequency-domain simulation first (with a source), to test if the coupling works, and then switch analysis type in both application modes from frequency-response to eigenfrequency.
If either of the application modes you are using does not support eigenfrequency analysis, you should continue to use frequency-response analysis, but set the frequency (omega_something) of that application mode to "lambda*i" in Scalar Variables dialog. COMSOL defines eigenvalue variable "lambda" as -i*omega in most eigenfrequency analyses, so this would be consistent with the rest.
Then, choose Eigenvalue solver in Solver Settings and use it as you normally would. Make sure that the "Eigenvalue name" is set to "lambda" (in Solver Settings, Eigenvalue tab).
If either of the application modes you are using does not support eigenfrequency analysis, you should continue to use frequency-response analysis, but set the frequency (omega_something) of that application mode to "lambda*i" in Scalar Variables dialog. COMSOL defines eigenvalue variable "lambda" as -i*omega in most eigenfrequency analyses, so this would be consistent with the rest.
Then, choose Eigenvalue solver in Solver Settings and use it as you normally would. Make sure that the "Eigenvalue name" is set to "lambda" (in Solver Settings, Eigenvalue tab).