# An Efficient Robust Solver for Optimal Control Problems for the Stokes Equations in the Time-Harmonic Case

## Dipl.-Ing. Wolfgang Krendl

June 18, 2013, 3:30 p.m. S2 059

In this talk we will construct a robust solver for the optimal control problem
for the Stokes equation, in the time-harmonic case. The discretization of the
corresponding optimality system leads to a large and sparse 8x8 block matrix
in saddle point form. We use an iterative solver, more precisely, we apply
the MINRES method. To gurantee efficiency, we constructed a preconditioner
for the MINRES-method, which is robust with respect to the mesh size, the
frequency $\omega$ and the control parameter $\alpha$. Numerical examples are given which
illustrate the theoretical results.