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Acoustic transducer and rock interaction

Posted Apr 11, 2020, 8:37 a.m. EDT Low-Frequency Electromagnetics, Acoustics & Vibrations Version 5.5 7 Replies

Danil Maksimov
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Hi, could you please help me with the selection of proper physics/coupling in the case of modeling acoustic wave propagation in solids (rock). Acoustic waves excited by the electrically powered transducer as shown in the figure.

I'have selected Pressure acoustic (actd)+Solid Mechanics (solid)+Electrostatics (es)+ Electrical Circuit (cir) interfaces.

Is it the correct way to model sound wave propagation in my case?

P.S. With this setup I am not able to obtain any pressure waves in the rock. Not sure what could be the reason. (No errors or warnings).

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7 Replies Last Post May 12, 2020, 11:58 a.m. EDT
Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago Apr 11, 2020, 10:30 a.m. EDT

Danil,

you don't need pressure acoustics. The waves in the rock are modeled with solid mechanics.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Danil, you don't need pressure acoustics. The waves in the rock are modeled with solid mechanics. Cheers Edgar
Danil Maksimov
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Posted: 4 years ago Apr 11, 2020, 11:23 a.m. EDT

Edgar, thank you for your reply!

May I ask you please, how can I model waves with the solid mechanics?

In the solid mechanics section nothing is related to acoustics (please see the figure). Or I should do something differently?

Thank you!

Edgar, thank you for your reply! May I ask you please, how can I model waves with the solid mechanics? In the solid mechanics section nothing is related to acoustics (please see the figure). Or I should do something differently? Thank you!

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Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago Apr 11, 2020, 11:53 a.m. EDT

If you excite the model in the frequency or time domain you will see the waves. Check the examples in the application library in Structural Mechanics > Elastic Waves. The time settings in the picture are only the output times of the solver. In wave problems you have to take care about proper time stepping in the solver. In most cases you need manual stepping and you cannot leave it to the solver to choose automatic stepping. Take care to use something like 10 steps per period and 6 mesh elements per wavelength. If you get a reasonable result you can try to relax that.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
If you excite the model in the frequency or time domain you will see the waves. Check the examples in the application library in Structural Mechanics > Elastic Waves. The time settings in the picture are only the output times of the solver. In wave problems you have to take care about proper time stepping in the solver. In most cases you need manual stepping and you cannot leave it to the solver to choose automatic stepping. Take care to use something like 10 steps per period and 6 mesh elements per wavelength. If you get a reasonable result you can try to relax that.
Danil Maksimov
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Posted: 4 years ago Apr 14, 2020, 2:10 p.m. EDT

Dear Edgar, thank you very much for your help! I think I've managed to model wave propagation in my case.

I have one more question, please. The figure attached displayed two scenarios of pressure waves propagation in the aluminium body with a round cavity (results are shown for the same timestep).

Left figure - the round cavity is "empty", cavity created by operation "difference". Right figure - the round cavity is filled with the material (plastic).

However, the results are displaying this cavity as "empty" (not grey colour) for both scenarios. The wave response also looks similar.

The question is it should be like this, or my simulation is not working for "filled" cave for some reason?

Thank you!

Best regards, Danil

Dear Edgar, thank you very much for your help! I think I've managed to model wave propagation in my case. I have one more question, please. The figure attached displayed two scenarios of pressure waves propagation in the aluminium body with a round cavity (results are shown for the same timestep). Left figure - the round cavity is "empty", cavity created by operation "difference". Right figure - the round cavity is filled with the material (plastic). However, the results are displaying this cavity as "empty" (not grey colour) for both scenarios. The wave response also looks similar. The question is it should be like this, or my simulation is not working for "filled" cave for some reason? Thank you! Best regards, Danil

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Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago Apr 14, 2020, 3:26 p.m. EDT

Danil,

it looks like the cavity is not part of the physics node. Check all assignments again. It is certainly possible to do what you want.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Danil, it looks like the cavity is not part of the physics node. Check all assignments again. It is certainly possible to do what you want. Cheers Edgar
Danil Maksimov
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Posted: 4 years ago May 12, 2020, 10:59 a.m. EDT

Dear Edgar, thank you very much for your help! Now everything is working fine =) Best regards, Danil

Dear Edgar, thank you very much for your help! Now everything is working fine =) Best regards, Danil
Edgar J. Kaiser Certified Consultant
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Posted: 4 years ago May 12, 2020, 11:58 a.m. EDT

Congratulations!

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Congratulations!

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