Parallel iterative solvers with selective blocking preconditioning for simulations of fault-zone contact

Iterative solvers with preconditioning are the most powerful choice for large-scale scientific computation, especially for parallel computing. In nonlinear problems such as contact simulations for geophysics, the condition numbers of the coefficient matrices are usually large due to special constraint conditions. The result is slow convergence of the iterative solver. In this study, a new pre-conditioning method, called selective blocking is developed along with a special partitioning method for parallel finite-element simulations on the GeoFEM plat-form. This newly developed method provides robust and smooth convergence and excellent parallel performance in 3D solid mechanics simulations for geo-physics with contact conditions performed on a Hitachi SR2201 parallel com-puter with 128 processing elements.