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My FRF study is not showing anything

Posted May 12, 2024, 12:38 p.m. EDT Studies & Solvers Version 6.2 3 Replies

Merna D
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Hello! Please help me, when i do a study for frequency domain, in my results- nothing is showign? it is saying pressure, discplacement etc. is all zero, i dont understand why? I have chosen the entire geometry when performing the study. And when i perform an eigenfrequency study for the same construction, i get results but not when i perform an frequency domain study.

3 Replies Last Post May 16, 2024, 9:57 a.m. EDT
Robert Koslover Certified Consultant
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Posted: 6 months ago May 12, 2024, 1:37 p.m. EDT
Updated: 6 months ago May 12, 2024, 1:42 p.m. EDT

Well, one (of many, many) causes of getting zeroes for all your computed variables is failure to specify any non-zero driving signal / source. Most physical systems simply "sit at rest" (so to speak) if there is nothing there to excite them. Eigenfrequency studies may not require you to specify an excitation, but most categories of Comsol models do.

I encourage you to post your .mph file to the forum so that it can be reviewed by others and so the issue(s) in your particular model will be easier to identify.

Also: Can you share what you mean by FRF in your context? The internet lists: "Frequency Response Function," "Fractional radiofrequency," and "Flat Rayleigh Fading," among other possibilities.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
Well, one (of many, many) causes of getting zeroes for all your computed variables is failure to specify any non-zero driving signal / source. Most physical systems simply "sit at rest" (so to speak) if there is nothing there to excite them. Eigenfrequency studies may not require you to specify an excitation, but most categories of Comsol models do. I encourage you to post your .mph file to the forum so that it can be reviewed by others and so the issue(s) in your particular model will be easier to identify. Also: Can you share what you mean by FRF in your context? The internet lists: "Frequency Response Function," "Fractional radiofrequency," and "Flat Rayleigh Fading," among other possibilities.
Acculution ApS Certified Consultant
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Posted: 6 months ago May 13, 2024, 3:20 a.m. EDT

As Robert says, you have probably forgotten an input node that drives the system, or forgotten to select a boundary/... in said node.

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René Christensen, PhD
Acculution ApS
www.acculution.com
info@acculution.com
As Robert says, you have probably forgotten an input node that drives the system, or forgotten to select a boundary/... in said node.
Merna D
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Posted: 6 months ago May 16, 2024, 9:57 a.m. EDT

Thank you for your responses, the issue has resolved now.

Thank you for your responses, the issue has resolved now.

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