A Trefftz-based numerical modelling framework for Helmholtz problems with complex multiple-scatterer configurations

The aim of the work presented in this paper is the numerical solution of low- and mid-frequency time-harmonic acoustic multiple-scattering problem. A novel so-called ‘multi-level’ modelling approach is proposed which is applicable to the study of a configuration of well separated obstacles of arbitrary shape on which any type of acoustic boundary condition can be applied. The generic character of the method is obtained by embedding the superposition principle for the multiple-scattering influence in a state-of-the-art acoustic modelling technique, the so-called Wave Based Method. The resulting approach successfully alleviates the geometrical limitations of the underlying Trefftz-based method and preserves the method’s computational efficiency, resulting in a generic multiple-scattering modelling framework with a superior computational efficiency in the low- as well as the mid-frequency range. Several numerical validation examples show that the proposed approach is as accurate as the classical single-scattering Wave Based Method and illustrate the computational efficiency as compared to Boundary Element Methods.