Multiscale modeling for a class of high-contrast heterogeneous sign-changing problems
It provides a numerical method for a challenging class of PDEs with sign-changing coefficients, relevant to metamaterial simulation, but the approach is an adaptation of an existing framework (CEM-GMsFEM).
The paper develops a multiscale finite element method for sign-changing PDEs arising in negative-index metamaterials, achieving robust performance for high-contrast coefficients. Numerical experiments confirm effectiveness and stability, with theoretical error bounds established via T-coercivity.
The mathematical formulation of sign-changing problems involves a linear second-order partial differential equation in the divergence form, where the coefficient can assume positive and negative values in different subdomains. These problems find their physical background in negative-index metamaterials, either as inclusions embedded into common materials as the matrix or vice versa. In this paper, we propose a numerical method based on the constraint energy minimizing generalized multiscale finite element method (CEM-GMsFEM) specifically designed for sign-changing problems. The construction of auxiliary spaces in the original CEM-GMsFEM is tailored to accommodate the sign-changing setting. The numerical results demonstrate the effectiveness of the proposed method in handling sophisticated coefficient profiles and the robustness of coefficient contrast ratios. Under several technical assumptions and by applying the \texttt{T}-coercivity theory, we establish the inf-sup stability and provide an a priori error estimate for the proposed method.