A comparison of time-domain hybrid solvers for complex scattering problems

In this paper the accuracy, efficiency and stability of two hybrid solvers are compared to FDTD in several complex scattering cases. The explicit hybrid solver, FD-FV, combines an unstructured FVTD, solver with FDTD, and the explicit-implicit solver, FD-FE, combines an unstructured FETD solver with FDTD. The results show that the two hybrid solvers are much more efficient than FDTD for complex objects where a Cartesian grid is not able to capture the geometry properly. Furthermore, they show that the FD-FE solver is a better choice than the FD-FV solver. Mainly because it is stable as long as the time step satisfies the CFL condition in the FDTD region, while the FD-FV solver may suffer from late time instabilities. But the FD-FE solver is also more efficient since the iterative method used to solve the matrix-vector system arising in FETD converges fast and the FVTD solver is heavily penalized by having to take shorter time steps to satisfy its CFL condition. Copyright (C) 2002 John Wiley Sons, Ltd.