An Effective Domain-Decomposition-Based Preconditioner for the FE-BI-MLFMA Method for 3D Scattering Problems

A domain-decomposition-based preconditioner (DDP) is presented for the hybrid finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA). The formulation of FE-BI is first approximated by the finite element method (FEM) with absorbing boundary condition (ABC). Then this approximate FEM-ABC formulation is solved by using the finite element tearing and interconnecting method (FETI). Finally, an inner-outer iterative algorithm with variable convergence threshold is designed for FE-BI-MLFMA. Because of good numerical scalability of FETI and good approximation of FEM-ABC, this DDP-FE-BI-MLFMA performs well even for large lossless objects.