An Advanced Wire-Mesh Model With the Three-Dimensional FDTD Method for Transient Analysis

Wire-mesh structures are found in the reinforced concrete of modern buildings. They can be part of lightning protection systems, and exhibit a shielding effect when being exposed to lightning electromagnetic (EM) pulses. Though there are plenty of methods available to analyze the EM characteristics of such structures, each method has its limitations. In this article, an advanced finite-difference time-domain (FDTD) wire-mesh model based on the impedance boundary condition is proposed for analyzing the lightning EM pulses in buildings. The wire mesh is regarded as an equivalent thin sheet. The material parameters in FDTD updating equations are modified with constant correction factors. A coarse FDTD mesh can then be assigned to reduce the cell number, enlarge the time step and improve the calculation efficiency significantly without compromising accuracy. Wire-mesh structures with multiple layers and/or junctions can also be considered in the model. With the proposed model, the EM pulses in a current induction case and a direct lightning stroke case are simulated. The validation with the thin-wire model is presented. It is observed that the proposed model consumes less than 20.74% memory space and 0.75% simulation time than the traditional thin-wire model. A desirable simulation accuracy can be achieved.