Modul: MAT870 Zurich Colloquium in Applied and Computational Mathematics

## Robust preconditioners for time harmonic wave propagation problems

Dr. Victorita Dolean Maini talk

Speaker invited by: Prof. Dr. Stefan Sauter

**Date:** 03.04.19 **Time:** 16.15 - 17.45 **Room:** Y27H25

Solving wave propagation problems in harmonic regime is a very challenging task because of their indefinite nature and highly oscillatory solution when the wavenumber k is high. Although there have been different attempts to solve them efficiently, we believe that there is no established and robust preconditioner, whose behaviour is independent of k, for general decompositions into subdomains. Several attempts have been made in the literature, e.g. by Conen et al (2014) for Helmholtz problems with heterogeneous coefficients or Graham et al. (2017) for Helmholtz equations and later on extended to Maxwell’s equations with specific boundary conditions but the mechanism and the limits of applicability of such methods are far from being fully understood. In this talk we will present a few recent methods and illustrate their application on several difficult examples.