Since the PSTD can use a coarser grid for large particles, it can lower the memory requirement in the calculation. It is found that the PSTD method is generally more accurate than the FDTD in calculation of the single-scattering properties given similar spatial cell sizes. The convolutional perfectly matched layer (CPML) absorbing boundary condition (ABC) is used to truncate the computational domain. In this study, a scattered-field finite-difference time-domain (FDTD) model and a scattered-field pseudo-spectral time-domain (PSTD) model are developed for light scattering by arbitrarily shaped dielectric aerosols.

The PL-CPML is shown to provide better reflection performance in both time-domain and frequency-domain evaluations than existing CPML in all of the numerical experiments.As fundamental parameters for polarized-radiative-transfer calculations, the single-scattering phase matrix of irregularly shaped aerosol particles must be accurately modeled.

The numerical reflection of the new piecewise-linear (PL) CPML is verified through a couple of experiments. Moreover, the accuracy performance is enhanced further by using optimal interpolation methods without computational efficiency trade-off.įor the second part of this dissertation, the CPML is reformulated using the PLRC method to improve absorption performance. The numerical experiments prove that the proposed subgridding scheme yields improved simulation accuracy and efficiency. The graded sub-grid mesh combined with H -field coupling is verified to have a superior stability margin.įor four different realistic electromagnetic problems, accuracy and efficiency estimations are carried out with respect to three implemented subgridding schemes. Next, a novel graded sub-grid mesh is proposed to increase the stability margin. Based on the in-depth investigation into the essential factors composing a subgridding scheme, a standard uniform subgridding scheme with E -coupling is implemented assuring stability by symmetric coupling. It is divided into two main parts: one is stable subgridding schemes, and the other is the convolutional perfectly matched layers (CPML) derived by piecewise linear recursive convolution (PLRC) technique.įirst, the basic background of a subgridding scheme is discussed by introducing several existing prominent subgridding schemes. In this dissertation, two methods for improving Finite-Difference Time-Domain (FDTD) simulations of electromagnetic problems are presented.

Cpml fdtd