A Spatially-filtered Finite-difference Time-domain Method with Controllable Stability Beyond the Courant Limit

• Main Author: Chang, Chun
• Other Authors: Sarris, Costas D.
• Language: en_ca
• Published: 2012
• Subjects: computational electromagnetics; finite-difference time-domain; spatial filtering; stability limit; CFL limit; CFL extension factor; subgridding scheme; FDTD; spatially-filtered FDTD method; spatially-filtered subgridding scheme; discrete cosine transform; discrete sine transform; discrete fourier transform; 0544
• Online Access: http://hdl.handle.net/1807/32460

This thesis introduces spatial filtering, which is a technique to extend the time step size beyond the conventional stability limit for the Finite-Difference Time-Domain (FDTD) method, at the expense of transforming field nodes between the spatial domain and the discrete spatial-frequency domain and removing undesired spatial-frequency components at every FDTD update cycle. The spatially-filtered FDTD method is demonstrated to be almost as accurate as and more efficient than the conventional FDTD method via theories and numerical examples. Then, this thesis combines spatial filtering and an existing subgridding scheme to form the spatially-filtered subgridding scheme. The spatially-filtered subgridding scheme is more efficient than existing subgridding schemes because the former allows the time step size used in the dense mesh to be larger than the dense mesh CFL limit. However, trade-offs between accuracy and efficiency are required in complicated structures.