混序全显BOR-FDTD算法的CPML/PML实现

Implementation of CPML/PML for Mixed–order Fully Explicit BOR–FDTD Algorithm

  • 摘要: 为改进时域有限差分(FDTD)算法在电磁波传播效率方面的不足,构建混序FDTD算法的卷积/完全匹配层(CPML/PML)实现,并应用至旋转对称(BOR)柱形结构。对BOR–FDTD算法的电磁场方程进行时域至频域的转换,进而对其频域方程进行坐标伸缩变换,并添加CPML/PML辅助函数后再次转换至时域。获取系数矩阵,并引入微扰项,得到两个子时间步下BOR–FDTD算法CPML/PML实现的新形式。通过数学变换,推导出混序全显BOR–FDTD算法的CPML/PML实现方程。算例证明,所提算法的CPML/PML实现与BOR–FDTD算法相比,在内存消耗近乎一致的情况下,最佳可提高效率约64%。所提算法在CPML/PML实现下呈现良好的电磁波吸收性能,均不超过–60 dB。

     

    Abstract: To address the limitations of the finite-difference time-domain (FDTD) algorithm in electromagnetic wave propagation efficiency, a convolutional/perfectly matched layer (CPML/PML) implementation is constructed for the mixed-order FDTD algorithm and applied to a body-of-revolution (BOR) cylindrical structure. First, the electromagnetic field equations of the BOR–FDTD algorithm are transformed from the time domain to the frequency domain, followed by coordinate scaling applied to the frequency-domain equations. Subsequently, after incorporating CPML/PML auxiliary functions, the modified frequency-domain equations are transformed back into the time domain. Second, a coefficient matrix is obtained, and a perturbation term is introduced, yielding a new form of the BOR–FDTD algorithm with CPML/PML implementation over two sub-time steps. Finally, through mathematical transformation, the CPML/PML implementation equations for the fully explicit mixed-order BOR–FDTD algorithm are derived. Numerical examples demonstrate that the proposed algorithm's CPML/PML implementation outperforms conventional BOR–FDTD algorithms, achieving an optimal efficiency improvement of 64% with nearly identical memory consumption. Moreover, under CPML/PML implementation, the proposed algorithm exhibits excellent electromagnetic wave absorption performance, with relative reflection errors consistently below –60 dB.

     

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