Domain Decomposition with Nonmatching Grids: Augmented Lagrangian Approach

We propose and study a domain decomposition method which treats the constraint of displacement continuity at the interfaces by augmented La- grangian techniques and solves the resulting problem by a parallel version of the Peaceman-Rachford algorithm. We prove that this algorithm is equivalent to the fictitious overlapping method introduced by P.L. Lions. We also prove its linear convergence independently of the discretization step h , even if the finite element grids do not match at the interfaces. A new preconditioner using fictitious overlapping and well adapted to three-dimensional elasticity problems is also introduced and is validated on several numerical examples.