SOME PRACTICAL ASPECTS OF PARALLEL ADAPTIVE BDDC METHOD

We describe a parallel implementation of the Balancing Domain Decomposition by Constraints (BDDC) method enhanced by an adaptive construction of coarse problem. The method is designed for numerically difficult problems, where standard choice of continuity of arithmetic averages across faces and edges of subdomains fails to main-tain the low condition number of the preconditioned system. Problems of elastic-ity analysis of bodies consisting of different materials with rapidly changing stiffness may represent one class of such challenging problems. The adaptive selection of con-straints is shown to significantly increase the robustness of the method for this class of problems. However, since the cost of the set-up of the preconditioner with adaptive constraints is considerably larger than for the standard choices, computational feasi-bility of the presented implementation is obtained only for large contrasts of material coefficients. 1