Tetsuyuki Kubota

A stable FDTD subgridding method for both spatial and temporal spaces

The proposed FDTD subgridding method is stable in both spatial and temporal spaces. Late-time instability has been resolved by separating the space and time interpolation interfaces from conventional collocated to same position. Numerical experiments conducted in 2D of 10 million time steps have no instability problem after a minimum gap distance for various refinement factors. Compare to existing subgridding methods the new method is not restricted to a single refinement factor and need no special treatment at material interfaces. This should open the FDTD subgridding method to more applications.

Development of CAD-to-CAE Model Preparation Technology

This paper explains and demonstrates how to reduce time for preparation of 3-dimensional (3D) geometrical Computer-Aided-Engineering (CAE) model from 3D Computer-Aided-Design (CAD) data. In generally, CAE model preparation is labor intensive and takes long time. Main part of preparation work is simplification of 3D-CAD data to decrease mesh scale and without impacting the solution accuracy. The purpose of this study is to create automatic CAE model preparation technology for reduction of preparation time. In this study, automatic model preparation method is developed by using of geometrical and topological information of 3D-CAD data. Benchmark test is performed to proof the efficiency of the method.

A stable three-dimensional subgridding method for both spatial and temporal spaces

In this paper we detailed a new three-dimensional Subgridding or Multigrid-FDTD method based on our recently proposed method in two-dimensions. First a 3D spatial subgridding method based on Monks two-dimensional method is described. Then by using conservation principle we showed the spatial subgridding method is stable, as well as the temporal subgridding method used. Finally, by separating the temporal and spatial perimeter interfaces for subgridding to different positions — the “temporal-spatial” coupled problem is decoupled into two separate independent problems. This decoupling makes the new 3D subgridding method naturally stable for electromagnetic wave propagation problems in both spatial and temporal spaces. Numerical results obtained show no late-time instability after ten million time steps.

A multilevel-multigrid approach to multiscale electromagnetic simulation

The time-dependent Maxwells equations are solved for mobile device applications using a multilevel-multigrid finite-difference time-domain (FDTD) method. For three-dimensional models that simulate system level details of mobile devices, the smallest features are in the nanometre (10−−9 m) range, leading to a time-step size in the attosecond (10−−18 s) range. The feature sizes of mobile devices are in the centimetre (10−−2 m) range, while for health and safety studies that include human models features are in the metre range.