This paper presents an alternative approach for the analysis of EM field by a rotating body with FDTD method and Overset Grid Generation method, considering Lorentz transformation for the higher velocity cases. This approach has been previously proposed for the case of linear and uniformly moving body against/to the incident wave. Here, the approach is expanded to a rotating body which includes the interpolation technique in the space and time increment along the cylindrical rotation at the fixed axis. First, the grid size ratios between the main mesh and the sub-mesh are studied. The appropriate choice of the grid size ratio is obtained. Then, the modulations of the EM field when the incident wave hits the rotating body in high velocity cases are analyzed. The relationship of the phase shift and the velocity is further observed. The observed EM fields are compared with the theoretical results and achieved good agreements in high relative velocities. The assessment of the numerical errors in a rotating environment is also highlighted. This numerical approach may have numerous situations to which it can be applied. This may be involved with the design of rotating devices such as microactuator, commutator and others.

Appropriate meshes are crucial for accurate and efficient 3D process simulation. In this paper, we present a set of tools operating on surface and interface triangulations. These tools allow the improvement of the accuracy of interfaces, the reduction of the number of triangles, and the removal of obtuse not coplanarily compensated triangles. The first tool is used within integrated topography simulation environments based on different data structures, e.g. cell-based and segment-based. The latter two are particularly important for providing appropriate input to mesh generation for 3D process simulation.

A new numerical approach for the analysis of electromagnetic scattering from a body moving in an arbitrary direction is described. A time dependent grid generation is applied to solve these problems. We are treating this method for a quasi-stationary field. Some numerical results are compared with the exact ones and excellent agreement between them is obtained.

This paper presents a new numerical procedure for solving the scattering wave by the moving surface. Recently, the author and her colleagues have proposed a novel numerical procedure of grid generation having a coordinate line coincident with an arbitrarily shaped moving boundary. The time dependent curvilinear coordinate system which coincides with a contour of moving boundary in a physical region is transformed into fixed rectangular coordinate system. The simple form for the transformation is made possible to choose the function between the physical region and the rectangular computational region. The FD-TD algorithm is exactly solved in this fixed rectangular coordinate system. In this paper, for the application of the FD-TD algorithm to the body fitted grid generation with moving boundary, the stability criterion of FD-TD algorithm for the body fitted grid generation with moving boundary in three dimensions is derived. The stability criterion is shown an upper bound for time step assuring stable numerical solutions. The study of scattering of electromagnetic and acoustic wave from a moving or a rotating body is very important for electromagnetic probing of moving body. The problem has been investigated in the past by numerous authors. One of them is solved by FD-TD method, where the linear interpolation is introduced for the movement. By using the presented transformation technique where time component is added to the grid generation, the time depending coordinate system can be transformed into fixed rectangular coordinate system. Then the problems are directly solved by FD-TD method in the transformed coordinate system. To verify this numemical technique, scattered field is evaluated in the case when a plane wave is normally incident on a moving perfectly conducting flat plate. The numerical results are compared with the exact ones and excellent agreement between them is obtained.

In a coherent optical communication system, a polarization fluctuation of an optical fiber is one of the most important problem. On the other hand, for a realization of optical devices, dielectric waveguides with sinusoidally varying width are investigated. Knowledge of the electromagnetic field distribution in a dielectric waveguide with boundary perturbed time by time becomes a very interesting problem. This paper shows a numerical method to simulate the effect of the external disturbance against the dielectric waveguide from time to time. The author has discussed body fitted grid generation with moving boundary for the Poisson's equation and the Laplace's equation. Here we apply this theory for the dielectric waveguide. The technique employs a kind of an expanded numerical grid generation. As the author added time component to grid generation, the time dependent coordinate system which coincides with a contour of moving boundary could be transformed into fixed rectangular coordinate system. Two cases of the perturbations against the dielectric waveguide are treated. In the first case, we present the electric distribution in the dielectric waveguide perturbed along a propagation path. While in the second case, the electric field in the waveguide perturbed perpendicular to the propagation path. Such phenomena that the phase of the electric field modulated by the external perturbation are clarified by numerical results. This technique makes it possible not only to analyze the effect of the external disturbance in a coherent optical communication system but also to fabricate optical modulators or couplers.