Localized adaptive radiation condition for coupling boundary and finite element methods applied to wave propagation problems

The wave propagation problems addressed in this paper involve a relatively large and impenetrable surface on which a comparatively small penetrable heterogeneous material is positioned. Typically the numerical solution of such problems is by coupling boundary and finite element methods. However, a straightforward application of this technique gives rise to some difficulties that are mainly related to the solution of a large linear system whose matrix consists of sparse and dense blocks. To face such difficulties, the adaptive radiation condition technique is modified by localizing the truncation interface only around the heterogeneous material. Stability and error estimates are established for the underlying approximation scheme. Some alternative methods are recalled or designed making it possible to compare the numerical efficiency of the proposed approach.