Improved Perfectly Matched Layers for Acoustic Radiation and Scattering Problems

M. Zampolli[1], N. Malm[2], and A. Tesei[1]
[1]NURC NATO Research Centre, La Spezia, Italy
[2]COMSOL AB, Stockholm, Sweden

Perfectly matched layers (PML) are an efficient alternative for emulating the Sommerfeld radiation condition in the numerical solution of wave radiation and scattering problems. The key ingredient of the PML formulation is the complex scaling function, which controls the anisotropic damping of the PML. The objective of this study is to propose a modified complex scaling function capable of providing the user with two advantages: (i) minimization of the spurious reflections at the physical domain-PML interface for propagating and evanescent fields at all angles of incidence and (ii) stability with respect to the frequency parameter which reduces the meshing effort in broadband applications. Numerical results are presented for radiation from a circular piston and for scattering from a rigid sphere. Overall, the modified formulation is more stable at lower frequencies, while some potential difficulties arising in high-frequency radiation problems remain to be addressed.