I have been working on modelling acoustics inside an acoustic mesh and I have tried this on both models, coupled with a structure and uncoupled standalone acoustic domain (interior problem). I define some impedance values on some surfaces of the acoustic mesh boundary and the remaining are defined as non-reflecting. Just to see what changing the impedance does to both models, I decided to reduce my impedance values by 50 times the original amount but I noticed no change on the pressure values in the history output. I admit, my physics of the problem is a bit shaky but still, I believe such a drastic change in impedance should cause changes in the pressure.
Note:
1. I am using an incident wave propogation as the excitation method, the wave is planar (ABAQUS states that this means it does not decay with distance unlike spherical waves).
2. My history output is taken at nodes inside the domain, NOT on the surface.
3. In the coupled acoustic-structural model, I defined the impedances on the acoustic mesh
4. I am doing a steady-state analysis in the frequency domain.
Best Regards
Khuldoon Usman
Dear Khuldoon,
Have a look at this article:
Article An introduction to the control of sound fields by optimising...
All the best,
Bashar
If you are modeling the sound field inside of a bounded domain (the interior problem), and then you illuminate the interior domain with a plane wave (as you say), then the acoustic source of the illumination is in effect far outside of the interior domain (because a plane wave is the limit of a very distant point source, or of an infinite plane wall).
If the incident field is coming from a source that lies outside of the interior domain, then is it not true that the boundary integral formulation of the sound field in the interior domain is zero? --- Here I am referring to the usual integral equation formulation exemplified for instance in equation A.8 and A.9 in the link Chapter Appendix: Acoustic Boundary Element Method
If the incident field comes from a source outside the interior domain, then your model-- if it is working correctly -- should be giving you zero field in the interior domain. In other words, your results are your model's approximation of the null field/ This null field will presumably be insensitive to impedance changes to the wall of the interior domain.
Try your tests again, this time placing an ideal point source near the center of your interior domain, rather than using a plan wave.
Thank you everyone for your guidance. It seems both the shared literature and explained physics has been clarified and I was able to solve the problem
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