Nested equivalence source approximation with adaptive group size for multiscale simulations

A nested equivalence source approximation (NESA) of the electric field integral equation with adaptive octree is explored for multiscale problems in this paper. The NESA low rank approximation formulation previously for far coupling groups with uniform size is derived for coupling groups with adaptive size, while preserves the kernel free and multiscale property. With the proposed adaptive group decomposition, reasonable separation of near and far region can be obtained. Numerical tests of the conformal and non-conformal multiscale electromagnetic simulation to show the validity of the adaptive NESA.