3D acoustic scaled boundary perfectly matched layer (SBPML) for acoustic-structure interaction problems

This work establishes a novel direct time-domain artificial boundary method for acoustic wave problems. The proposed method, called scaled boundary perfectly matched layer (SBPML), is more generalized and flexible than the conventional perfectly matched layer (PML). This work originates from an extension of recently proposed SBPMLs for wave problems in solid medium and fluid-saturated poroelastic media. The acoustic SBPML is constructed by combining the scaled boundary coordinates transformation inspired by the scaled boundary finite element method (SBFEM) with the complex coordinate stretching technology from the PML. This method directly constructs the complex coordinate stretching function in the scaled boundary coordinates, eliminating the reliance of existing PMLs on the global coordinate system. As a result, this method can accommodate artificial boundaries with general geometries and consider planar physical surfaces and interfaces that may exist in infinite acoustic domains. Moreover, it also can be described as a second-order mixed unsplit-field form of the acoustic pressure-velocity field in time, which can be seamlessly coupled with the finite-element equations of the bounded domains. Numerical examples are presented to demonstrate the accuracy and potential of the proposed method in dealing with the interaction problems in infinite acoustic domains.