Optimized Schwarz methods for a diffusion problem with discontinuous coefficient

Gander, Martin ; Dubois, Olivier

In: Numerical Algorithms, 2015, vol. 69, no. 1, p. 109-144

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    Summary
    We study non-overlapping Schwarz methods for solving a steady-state diffusion problem in heterogeneous media. Various optimized transmission conditions are determined by solving the corresponding min-max problems; we consider different choices of Robin conditions and second order conditions. To compare the resulting methods, we analyze the convergence in two separate asymptotic regimes: when the mesh size is small, and when the jump in the coefficient is large. It is shown that optimized two-sided Robin transmission conditions are very effective in both regimes; in particular they give mesh independent convergence. Numerical experiments are presented to illustrate and confirm the theoretical results.