An Optimized Higher Order PML in Domain Decomposition WLP-FDTD Method for Time Reversal Analysis

In this paper, an efficient higher order complex frequency shifted (CFS) perfectly matched layer (PML) derived from a stretched coordinate formulation is proposed for the unconditionally stable finite-difference time-domain method based on weighted Laguerre polynomials. The higher order CFS-PML, which is implemented with an auxiliary differential equation (ADE) approach, has apparent advantage in reducing late-time reflections compared with the standard unsplit-field PML and lower order CFS-PML. Furthermore, the parameter values of stretching functions in the higher order ADE-CFS-PML are optimized with the multiobjective genetic algorithm to improve absorbing performance. The optimal solutions can be chosen from the Pareto front for trading-off between two independent objectives. The numerical formulation is derived and its absorbing ability is validated through three numerical tests. Moreover, the proposed higher order PML can be placed very close to the objects and the simulation area can be further reduced accordingly. Numerical examples of time reversal wave propagation in a real indoor environment are included to validate the accuracy and efficiency of the proposed scheme.