Some observations on ORAS and SORAS preconditioners for solving high-frequency Helmholtz equation (Shihua Gong, University of Bath)

03.03.2020 14:00 – 15:00

Helmholtz problems are particularly difficult to precondition effectively for two main reasons: the high indefiniteness of the non-hermitian linear system and the instability of the local Dirichlet or Neumann problems. Optimised Schwarz methods (OSM) introduce optimized interface conditions not only improving the stability of the local problems but also maximizing the rate of the convergence of a domain decomposition iteration. In this talk, some results on two OSM-type preconditioners: ORAS and SOARS (also called as OBDD-H) will be presented. We will also explain the importance of “nearly normal” preconditioning for these non-self-adjoint problems.

Lieu

Room 623, Séminaire d'analyse numérique

entrée libre