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effect of pml thickness and meshing in acoustics-structural module

Posted Mar 1, 2015, 2:45 p.m. EST Acoustics & Vibrations, Mesh, Parameters, Variables, & Functions Version 4.4 4 Replies

Sandesh Gopinath
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Hi everyone,
I am trying to simulate the frequency response of a thin membrane using acoustic-structural interaction module.The issue is with meshing of all domains and the pml thickness levels.
For my model,changing mesh from normal to fine changes the frequency response drastically.And also just increasing the pml thickness from 5mm to 10 mm also changes the response a lot.
I am checking the response by measuring the sound pressure level between 1-16 khz at a point at the beginning of the pml layer.
Can any one advise me on these issues,or are these things expected to be the way they are.
Thanks for the help,
Sandesh

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4 Replies Last Post Mar 2, 2015, 5:13 p.m. EST
Sergei Yushanov Certified Consultant
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Posted: 10 years ago Mar 2, 2015, 9:39 a.m. EST
Sandesh,

There are certain requirements on mesh for wave-type problems:
-place 5-6 elements thought the thickness of PML
-use Swept mesh for PML domains
-resolve wavelength (at least 6 second order elements per wavelength)

None of the above is fulfilled in your model. Attached is modified file which shows that pressure distribution is independent on thickness of PML.

Regards,
Sergei
Sandesh, There are certain requirements on mesh for wave-type problems: -place 5-6 elements thought the thickness of PML -use Swept mesh for PML domains -resolve wavelength (at least 6 second order elements per wavelength) None of the above is fulfilled in your model. Attached is modified file which shows that pressure distribution is independent on thickness of PML. Regards, Sergei
Sandesh Gopinath
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Posted: 10 years ago Mar 2, 2015, 2:20 p.m. EST
Thank you sergei.
Can you please attach the modified file.
Thank you sergei. Can you please attach the modified file.
Sergei Yushanov Certified Consultant
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Posted: 10 years ago Mar 2, 2015, 2:30 p.m. EST
Sandesh,

Attached is modified file.

Regards,
Sergei
Sandesh, Attached is modified file. Regards, Sergei

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Sandesh Gopinath
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Posted: 10 years ago Mar 2, 2015, 5:13 p.m. EST
Thank you Sergie.The model works like a charm.
I actually want to sweep through frequencies,so would the mesh adapt itself for every frequency automatically or do i have to make some changes?
Thank you Sergie.The model works like a charm. I actually want to sweep through frequencies,so would the mesh adapt itself for every frequency automatically or do i have to make some changes?

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