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How to create a video of acoustic/elastic wave propogation in poroelastic material and tunnels.
Posted Aug 24, 2018, 5:04 p.m. EDT Acoustics & Vibrations, Geomechanics 1 Reply
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Hello, I'm trying to simulate resonating sound waves in a rabbit burrow for my lab. I've successfully done this with the poroelastic-solid-acoustic wave multiphysics setup, but this uses frequency domain. It would be extremely helpful for us to be able to watch the propogation of the wave, so I tried using a transient acoustic block in place of the frequency domain . This resulted in an extremely long simulation time and the file reaching sizes of several dozen gigabytes.
(File PourousBunnyTimeTrans.mph)
I figured this was due to either incorrect implementation of the transient block or the poroelastic module interaction being too complex, so I tried toning it down. Instead, I just did an acoustic-solid interaction multiphysics simulation accepting that I'd lose the added accuracy of modeling soil as a poroelastic material. This went well but didn't give "Sound Pressure" as a possible output to plot, which is what we'd been using to visualize resonance up till now.
file: BunnyTimeTrans.mph
I tried to get the sound pressure back by running a simulation with both the transient and the frequency domain components by using a modal transient analysis. This yielded the following error "Time-dependent equation residual vector is not supported for modal analysis."
file: BunnyTimeTransFreq.mph
Does anyone know how to fix this error, or a better way to simulate the scenario of a block of dirt with a cylinder of air in it being excited by a plane wave source from the top so that I view the propogation of the sound wave through the dirt and/or cylinder of air?
Thank you, Daniel Magley
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Daniel,
you might try running a frequency sweep using the Fourier transform of some excitation pulse to excite the frequency domain study. Afterwards use an inverse FFT step to transform into time domain. We successfully did this for an electromagnetic, solid, acoustic coupled model.
Putting it all together will be a little tedious though. And of course the calculation time will multiply by the number of frequency steps you need to resolve the excitation pulse and runtime of the transient.
Cheers Edgar
-------------------Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com