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PML in acoustic modeling
Posted Jan 23, 2024, 1:01 p.m. EST Acoustics & Vibrations, Modeling Tools & Definitions 1 Reply
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I am simulating an infinite metamaterial in Comsol to address the scattering problem, requiring non-reflecting boundary conditions on the right side, considering an incident angle theta. While exploring non-reflecting boundary conditions for truncated domains, I came across a statement in the reference manual cautioning against using Perfectly Matched Layer (PML) regions for non-uniform media. Here is the statement:
"The PML region is designed to model uniform regions extended toward infinity. Avoid using objects with different material parameters or boundary conditions that influence the solution inside a PML region. "
Now assume that one of the media in the scattering problem that I am trying to solve is non-homogeneous. I mean its material properties is a function of spatial coordinates (Like phononic crystals). Now, from this sentence that I quoted from the reference book I understand that the PML is not applicable here. If I am right, how should I impose non-reflecting boundary conditions on infinite domains when the domain is non-homogeneous?
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Hi Kimya,
Acoustic metamaterials are usually modeled by one of the following ways:
1) model the bandgap structure of an infinite array by considering a periodic unit cell with Floquet periodicity
2) model some finite sized array, and include coupling to exterior fluid domains with uniform properties where standard PMLs are applicable.
Both of these techniques are used in the following example: https://www.comsol.com/model/sonic-crystal-16925
Hope this helps,
-Mark