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Acoustic plane radiation boundary conditions equation reference.

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Hi, all,

I applied an acoustic plane wave radiation boundary condition to my model in a frequency domain study.
However, when I look at the equations, I could not understand why in the frequency domain study, the plane wave equation is defined as a second order equation with the Laplace operator. (as the attached file)
I can understand the first-order radiation boundary conditions in the frequency domain they use comes from the momentum conservation.
But why they used the second-order equation in the frequency domain study, and how does it come from?

I've read the reference paper they cited, however, I would appreciate if someone can give me more explanations, hints or some other reference sources.

Comsol 4.2 equation reference :

Acoustics Module Users Guide/ Pressure Acoustics Branch/ The Pressure Acoustics Interface/ Plane, Spherical, and Cylindrical Radiation Boundary Conditions .

Thanks a lot in advance.



0 Replies Last Post 29 giu 2012, 11:09 GMT-4
COMSOL Moderator

Hello Jen-Hsuan Ho

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