Block LU Preconditioners for Symmetric and Nonsymmetric Saddle Point Problems

In this paper, a block LU preconditioner for saddle point problems is presented. The main diierence between the approach presented here and that of other studies is that an explicit, accurate approximation of the Schur complement matrix is eeciently computed. This is used to compute a preconditioner to the Schur complement matrix that in turn deenes a preconditioner for a global iteration. The results indicate that this preconditioner is eeective on problems arising from CFD applications.