Xinbo He

Ferrites can absorb electromagnetic waves and require accurate modeling for their simulation. This can be achieved by combining the shift operator (SO) approach with the discontinuous Galerkin time-domain (DGTD) method. Herein, the time-domain constitutive relation for the permittivity of magnetized ferrite is derived. In the main coordinate system, the material exhibits anisotropy and dispersion. The corresponding time-domain iterative formulation for DGTD applied to magnetized ferrite is presented. The algorithm is validated through the example of backscattering from a magnetized ferrite cylinder under 2-D transverse magnetic (TM) wave. Additionally, the electromagnetic scattering from a Von Karman-shaped conducting cylinder coated with magnetized ferrite is simulated, and the scattering characteristics are examined. Results indicate thattheradar cross section (RCS) is influenced by factors such as the presence of coating, precession angular frequency $\omega _{0} $ , material parameter $\omega _{\textrm {m}} $ , and the angle of electromagnetic wave incidence.

A fast cylindrical explicit and unconditionally stable finite-difference time-domain (FDTD) method that accommodates fine structures is proposed. This method introduces a general domain decomposition strategy derived from an analysis of the spectral radius of cylindrical grids. This strategy applies to a wide range of grid discretizations, especially in cases involving fine grids. By doing so, all unstable modes can be obtained by solving the eigenvalue problem in one subdomain, significantly reducing the computational complexity. Two explicit field-iteration schemes are also presented. In addition, the boundary fields between subdomains require no additional correction. Numerical results demonstrate the validity and efficiency of the proposed method.

Aiming at the electromagnetic computation problem of multilayer metal meshes due to the multiscale structure and the existing dispersion model's difficulty in accurately fitting the transmittance characteristics of dielectric-background multilayer metal meshes (DBMMM) in a wide frequency range, a novel time-domain scheme utilizing a linear loss dispersion model is proposed for the transmittance characteristics of DBMMM. The fine structure is eliminated by replacing the composite structure of DBMMM with a single-layer dispersive medium, then a coarser grid can be employed to calculate the transmission characteristics of complex structures containing fine metal mesh structures. Compared with existing dispersion models, the proposed linear loss dispersion model exhibits enhanced adaptability. Also, compared with existing equivalent methods, the presented algorithm can be applied to a wider frequency range and has higher calculation accuracy. Compared with the traditional finite-difference time-domain (FDTD) method, the proposed method has the speedup of 117.58 and the memory occupation of 11.19%.

Accurately and efficiently solving the physical characteristics of electromagnetic railguns is essential for understanding their dynamic behavior and ensuring reliable design. However, an effective real-time solution for the multiphysics coupling characteristics of electromagnetic railguns has yet to be proposed. This article develops a modified set of governing equations for electromagneticthermal coupling based on the arbitrary LagrangianEulerian (ALE) dynamic mesh framework and applies them to the transient electromagnetic launch process. Additionally, a hybrid meshing strategy combining sliding and dynamic meshes is introduced, where sliding meshes are utilized for the armature region and the rail sections in contact with the armature, while dynamic meshes are applied to the remaining rail sections. This approach effectively balances computational accuracy and complexity, enabling precise real-time solutions for the multiphysics characteristics of transient and high-speed models. To validate the proposed method, numerical results from static meshes, single-physics simulations, and the modified multiphysics coupling solution are compared with experimental data. The results demonstrate the effectiveness and efficiency of the proposed approach in achieving accurate and real-time multiphysics simulations of electromagnetic railgun launches.

The Airy light-sheet is known for its unique properties, such as non-diffraction, self-acceleration, and self-healing, making it valuable in imaging and particle manipulation. However, most existing scattering studies focus on symmetric spherical particles using analytical models, overlooking irregular particles commonly found in biological systems. In this work, we develop a finite-difference time-domain (FDTD) framework to construct a two-dimensional Airy light-sheet using the vector angular spectrum method and the total-field/scattered-field (TF/SF) technique. The reconstructed Airy light-sheet in FDTD agrees well with theoretical predictions. We further analyze near-field scattering from two representative models—the square-shaped particle and the red blood cell particle under varying parameters. This study provides a flexible tool for structured light interaction with irregular particles, expanding FDTD applications in biophotonics and optical trapping.

In computational electromagnetics, the finite-difference time-domain (FDTD) method is recognized for its volumetric discretization approach. However, it can be computationally demanding when addressing large-scale electromagnetic problems. This paper introduces a novel approach by incorporating Graphic Process Units (GPUs) into an FDTD algorithm. It leverages the Compute Unified Device Architecture (CUDA) along with OpenMPI and the NVIDIA Collective Communications Library (NCCL) to establish a parallel scheme for the FDTD algorithm in distributed cluster GPUs. This approach enhances the computational efficiency of the FDTD algorithm by circumventing data relaying by the CPU and the limitations of the PCIe bus. The improved efficiency renders the FDTD algorithm a more practical and efficient solution for real-world electromagnetic problems.

This paper presents a parallel ray tracing (RT) algorithm based on a graphic processing unit (GPU) applied to electromagnetic scattering calculations in an inhomogeneous plasma to enhance the computational efficiency of the algorithm. The proposed algorithm utilizes a fourth-order Runge–Kutta method to solve the Haselgrove equation to track ray paths within the inhomogeneous plasma and implements parallel processing of the RT procedure using GPU. By independently assigning single threads to the rays originating from the vertices and the midpoints of each triangulated ray tube, a substantial number of rays are traced in parallel to reduce the algorithm runtime. The results indicate that the parallel RT algorithm based on GPU significantly enhances computation efficiency in inhomogeneous plasma while maintaining accuracy.