## Generating visible waves from an acoustic waveguide

General discussion about Elmer
kevinarden
Posts: 1210
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### Re: Generating visible waves from an acoustic waveguide

Elmer itself is unitless, but your material constants are SI so length should be meters.
In the unv file node 1 is 50.8, 50.8, node 6 is 50.8, -50.8
node 2 is 0, 9.5625 and Node 5 is 0, -9.525
so scaling by 0.001 would give mm
-1
2411
1 1 1 11
5.0799999999999997D+01 5.0799999999999997D+01 0.0000000000000000D+00
2 1 1 11
8.5635224561320102D-15 9.5250000000000004D+00 0.0000000000000000D+00
3 1 1 11
5.0800000000000303D+01 2.0000000000000000D+03 0.0000000000000000D+00
4 1 1 11
5.0799999999999699D+01 -2.0000000000000000D+03 0.0000000000000000D+00
5 1 1 11
6.2305702972287401D-15 -9.5250000000000004D+00 0.0000000000000000D+00
6 1 1 11
5.0799999999999699D+01 -5.0799999999999898D+01 0.0000000000000000D+00
Gary R
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Location: Long Beach CA, USA

### Re: Generating visible waves from an acoustic waveguide

OK I'm confused. Attached are two screen shots of the solution at 2000 Hz. One is of the magnitude and the other of the X vector only. The magnitude shows very little in the way of wave motion. The X vector shows strong periodic wave motion and corresponds to the proper number of waves for the 2 m distance of the model. The Y vector seems to be exactly out of phase with the X vector leaving the magnitude equal to zero. I am not sure how to interpret this. Associating X and Y pressure vectors with X and Y Cartesian measurements is not computing well in my brain. It would seem that the magnitude would be the only thing of importance as far as sound volume is concerned. If that is true then the output of the waveguide is essentially zero. I find that hard to believe. At 3KHz the simulation starts to fail, which was pointed out earlier.

Comments would be sincerely appreciated.

Gary R.
Attachments
Helmholtz2000X.png
X vector only
Helmholtz2000Mag.png
Magnitude of X and Y vectors
raback
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### Re: Generating visible waves from an acoustic waveguide

Hi

Paraview does not support complex numbers so you should think of _x as the Real component and _y as the Imaginary component.

-Peter
Gary R
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Joined: 12 Apr 2012, 07:23
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Location: Long Beach CA, USA

### Re: Generating visible waves from an acoustic waveguide

Thanks Peter. Makes sense. I guess the only thing left to do is adjust the mesh for higher frequencies.

Gary R