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Please Help, Eigen frequency of Fluid filled micropipette

Posted Jul 30, 2012, 8:28 p.m. EDT Structural Mechanics Version 4.1 3 Replies

Sankha Mukherjee
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Hello everyone,

I am trying to simulate the natural frequencies of a micropipette when it's filled with liquids. So far, I have used Fluid structure interaction physics plus solid mechanics physics to do the analysis. However, when I run the simulation I get weird shapes and error messages. The results show that the natural frequency of the fluid filled piepete is the same as the eigen frequency of the pipette without fluid. But this does not make sense, because resonance frequency should decrease when fluid is introduced because of the added mass of the fluid. Can anyone tell me as to what simulation steps should be used? What conditions should be used? Can anyone share a model (as a benchmark model) to show how these types analysis need to be done? I browsed through the blog, but, there seems to be no model to touch upon this topic.

-Sankha

3 Replies Last Post Aug 2, 2012, 2:39 p.m. EDT
Sankha Mukherjee
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Posted: 1 decade ago Aug 1, 2012, 8:47 p.m. EDT
Hello Everyone,

I am attching my model herewith. Please have a look and provide your suggestions.

Thanks

Sankha
Hello Everyone, I am attching my model herewith. Please have a look and provide your suggestions. Thanks Sankha
Sankha Mukherjee
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Posted: 1 decade ago Aug 2, 2012, 1:00 p.m. EDT
Sorry, I forgot to attach the model. Attaching it herewith.



-Sankha
Sorry, I forgot to attach the model. Attaching it herewith. -Sankha

Attachments:

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Aug 2, 2012, 2:39 p.m. EDT
Hi

obviously you have not managed to couple the physics correctly. In the later version 4 you can add a "boundary mass" to mimic the extra mass of the liquid, but you might need the acoustic module to get the complete coupling running, pre-cooked by COMSOL

--
Good luck
Ivar
Hi obviously you have not managed to couple the physics correctly. In the later version 4 you can add a "boundary mass" to mimic the extra mass of the liquid, but you might need the acoustic module to get the complete coupling running, pre-cooked by COMSOL -- Good luck Ivar

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