**On Wednesday, 5 February 2020 at 11:00 Lea Miko Versbach will talk on the topic “Implicit DG solvers and multigrid preconditioners” **

**Location: **Gyrhofstraße 8a (Gebäude 158a), Room 1.105 (1st floor), 50931

**Abstract: **In this talk I will give an introduction to implicit DG solvers and the challenges which arise when solving the large nonlinear systems coming from the implicit temporal discretization. We will solve these system using a Jacobian-free Newton-Krylov method. The problem with this method is that the Krylov subspace method converges slowly for discretized PDEs. In order to speed up computations, we need to construct preconditioners. This can be done using iterative methods. Carefully constructed multigrid methods are cheap and effective preconditioners. I will explain more details about the construction of these preconditioners and show some numerical results.