FEM-BEM mortar coupling for the Helmholtz problem in three dimensions

Lorenzo Mascotto; Jens Markus Melenk; Ilaria Perugia; Alexander Rieder

doi:10.1016/j.camwa.2020.04.014

paper

FEM-BEM mortar coupling for the Helmholtz problem in three dimensions

arXiv:2004.03523 · doi:10.1016/j.camwa.2020.04.014

Abstract

We present a FEM-BEM coupling strategy for time-harmonic acoustic scattering in media with variable sound speed. The coupling is realized with the aid of a mortar variable that is an impedance trace on the coupling boundary. The resulting sesquilinear form is shown to satisfy a Garding inequality. Quasi-optimal convergence is shown for sufficiently fine meshes. Numerical examples confirm the theoretical convergence results.