  T. Borrvall and J. Petersson [Topology optimization of fluids in Stokes flow,
International Journal for Numerical Methods in Fluids 41 (1) (2003) 77--107]
developed the first model for topology optimization of fluids in Stokes flow.
They proved the existence of minimizers in the infinite-dimensional setting and
showed that a suitably chosen finite element method will converge in a weak(-*)
sense to an unspecified solution. In this work, we prove novel regularity
results and extend their numerical analysis. In particular, given an isolated
local minimizer to the analytical problem, we show that there exists a sequence
of finite element solutions, satisfying necessary first-order optimality
conditions, that strongly converges to it. We also provide the first numerical
investigation into convergence rates.
