基于亚网格时域有限差分法的改进雷电电磁脉冲计算模型  

Improved Computational Model of Lightning Electromagnetic Pulse Based on Subgridding Finite-Difference Time Domain Method

作　　者：刘银萍 高骐森 蒋雨卉 LIU Yin-ping;GAO Qi-sen;JIANG Yu-hui(China Meteorological Administration Aerosol-Cloud-Precipitation Key Laboratory,School of Atmospheric Physics,Nanjing University of Information Science&Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学大气物理学院中国气象局气溶胶与云降水重点开放实验室,南京210044

出　　处：《科学技术与工程》2023年第9期3648-3654,共7页Science Technology and Engineering

基　　金：江苏省自然科学基金青年科学基金(BK20150903);江苏省高校自然科学研究面上项目(15KJB170010);国家自然科学基金面上项目(41575004)。

摘　　要：在利用均匀网格时域有限差分法(finite-difference time domain,FDTD)计算地闪回击电磁脉冲时,空间步长选取较大会导致计算结果中后期出现震荡,所以为了计算结果的准确必须采用较小的空间步长,导致计算效率低、内存需求大。为了解决这一问题,提出利用惠更斯亚网格技术改进计算模型,改进后的模型可以实现在距离雷电通道近、高频分量多的区域采用较小的空间步长,其余区域仍采用较大的空间步长,从而以较高的计算效率消除计算结果中后期的震荡。首先,分析了空间步长对均匀网格FDTD法的各个场分量计算结果的影响;其次,通过与均匀网格FDTD计算结果对比,深入研究了改进模型对水平电场中后期震荡的消除作用。结果表明:随着步长的增大,水平电场中后期震荡剧烈;在不同地面电导率、地闪回击速度下,改进后的计算模型均能以较高的计算效率得到准确的、无震荡的计算结果。The oscillations occur in the middle and late stage of the calculation result when a large space step is used in the uniform grid finite-difference time domain(FDTD)to calculate the lightning electromagnetic pulse.Therefore,a smaller space step must be adopted for the accuracy of the calculation result,which will in turn results in low calculation efficiency and large memory requirement.Huygens subgridding technique was used to improve the calculation model in order to solve this problem.The improved model can adopt a smaller space step in the area close to the lightning channel and with more high-frequency components,and still adopt a larger space step in other areas,thus eliminating the oscillations in the middle and later stages of the calculation results with higher efficiency.Firstly,the influence of space step size on the calculation results of the uniform grid FDTD method was analyzed.Then,by comparing with the calculation results of the uniform grid FDTD,the elimination effect of the improved model on the oscillations of the horizontal electric field was studied in-depth.The results show that with the increase of step length,the horizontal electric field oscillates violently in the middle and later stages.Under different ground conductivity and lightning return velocity,the improved calculation model can obtain accurate and non-shock calculation results with high calculation efficiency.

关 键 词：雷电电磁脉冲 时域有限差分 空间步长 亚网格技术 

分 类 号：P427.3[天文地球—大气科学及气象学]