A perfectly matched layer formulation adapted for fast frequency sweeps of exterior acoustics finite element models

Highlights: • Finite Element formulation for simplified exterior acoustic problems. • Parameter-free perfectly-matched layer (PML) adapted for fast frequency sweeps. • A priori indicator for the choice of approximation frequencies for the PML. • Criteria for the discretization in connection with the size of the domain and PML. • Validation on a range of 2D and 3D applications. -- Abstract: Effective treatment of unbounded domains using artificial truncating boundaries are essential in numerical simulation, e.g. using the Finite Element Method (FEM). Among these, Perfectly Matched Layers (PML) have proved to be particularly efficient and flexible. However, an efficient handling of frequency sweeps is not trivial with such absorbing layers since the formulation inherently contains coupled space- and frequency-dependent terms. Using the FEM, this may imply generating system matrices at each step of the frequency sweep. In this paper, an approximation is proposed in order to allow for efficient frequency sweeps. The performance and robustness of the proposed approximation is presented on 2D and 3D acoustic cases. A generic, robust way to truncate the acoustic domain efficiently is also proposed, tested on a range of test cases and for different frequency regions.