# Johann Moulin participates to the FreeFem++ days

The efficient iterative resolution of saddle-point problem arising when addressing the stability analysis of incompressible flows is addressed using a class of preconditioner, the so-called Augmented Lagrangian preconditioner. It has been implemented with the FreeFem++ software, in a parallel computing environment, thanks to an interface with the PETSc library, developed by P. Jolivet.

The slides of the talk are available here.

In the figures below, we report the computational time and memory of the iterative parallel preconditionner (GMRES + AL) compared to the use of the direct solver MUMPS, for computing a steady solution (left) and computing eigenvalues (right)

The full programm of the “FreeFem++ Days” is here https://www.ljll.math.upmc.fr/~hecht/ftp/ff++days/2017/Schedule.html