\mathcal H -Matrices Compressed Multiplicative Schwarz Preconditioner for Nonconformal FEM-BEM-DDM.

An \mathcal H -matrices compressed multiplicative Schwarz (MS) preconditioner for the nonconformal finite-element method (FEM)–boundary element method (BEM)–Domain decomposition method (DDM) is proposed to analyze the electromagnetic radiation and scattering from periodic structures such as frequency-selective surfaces (FSSs) or antenna arrays. To improve the overall convergence, an MS preconditioner is proposed for the DDM matrix. The hierarchical matrix ( \mathcal H -matrices) technique is introduced into the preconditioned system to compress the dense matrices to further improve the efficiency. Moreover, a finite-element tearing and interconnecting like algorithm is adopted to eliminate the interior volumetric FEM unknowns and the multilevel fast multipole algorithm is integrated to reduce the computational complexity of BEM. Numerical examples are presented to validate the proposed method. It is observed that this method exhibits superior performance and consumes far less memory and CPU time than the traditional implementation. [ABSTRACT FROM PUBLISHER]