A Finite Element–Boundary Integral Solver for CO₂ Plume Monitoring in Multilayered Anisotropic Media

This repository contains the complete source code and data for EMPACK 2020, a Finite Element–Boundary Integral (FEBI) solver for electromagnetic simulation of CO₂ plume monitoring scenarios in multilayered anisotropic subsurface media. The solver couples a volumetric Finite Element Method (FEM) for the heterogeneous CO₂ plume region with a Boundary Integral (BI) formulation based on the layered-medium Green's function, enabling efficient multiscale modelling without a full-domain FEM mesh. Sommerfeld integrals are evaluated using an acceleration scheme with asymptotic extraction. Three numerical examples are fully reproduced: Multiscale problem in an anisotropic multilayered medium Validation against an independent FEM reference (nested CO₂ plume model) Sensitivity analysis for CO₂ plume detection as a function of plume size and anisotropy ratio The archive includes: Fortran 90 solver source code, pre-build library for LMGF, pre-generated FEM meshes, ready-to-run solver input files, MATLAB pre/post-processing scripts, and COMSOL near-field reference data for validation. Software dependencies: Intel oneAPI 2024.2 (ifx compiler + MKL), CMake ≥ 3.10, MATLAB R2022b or later.