摘要
提出混合ADI-FDTD亚网格技术开展频散介质GPR正演,即在物性参数变化剧烈局部区域采用细网格剖分ADI-FDTD计算,其他的区域采用粗网格剖分常规FDTD计算,ADI-FDTD突破了CFL条件的限制,可选取与粗网格一致的大时间步长,有效地提高了计算效率.本文首先基于Debye方程,推导了粗网格FDTD及细网格ADI-FDTD频散介质差分格式,着重对粗细两种网格结合的场值交换方式进行了深入探讨,给出了该算法的计算流程.然后以一个薄层模型为例,分别应用粗网格、细网格、混合ADI-FDTD亚网格算法对该模型进行正演,计算资源的占用及模拟精度说明了混合ADI-FDTD亚网格算法的优势.最后,建立频散介质与非频散介质的组合模型,应用3种方法对该模型进行正演,对比3种方法优劣,分析雷达剖面中非频散介质及频散介质中波形特征,有效地指导雷达资料的精确解释.
Abstract A hybrid ADI-FDTD sub-gridding method is proposed to improve strong dispersion medium GPR forward simulation, which uses fine mesh ADI-FDTD in the partial region of dramatic physical parameter changes, and coarse mesh FDTD in other regions, because the ADI- FDTD is not limited by CFL stability condition and we can choose larger time step according to coarse mesh to improve computational efficiency. This paper mainly discussed the field value exchange of the combined coarse mesh and fine mesh and gave out the calculation procedure of the algorithm, through studying the radar wave based on Debye equation, then deduced the coarsemesh FDTD and fine mesh ADI-FDTD difference scheme of frequency dispersion media. Choosing a thin layer model as an example, we applied coarse mesh, fine grid and hybrid ADI-FDTD subgridding separately in forward simulation~ the computing cost and the simulation accuracy clearly show the advantages of the hybrid ADI-FDTD subgridding method. Finally, we established the dispersion media and non-dispersion media composition model, applied three methods in these two models, and compared the advantages and disadvantages of three methods to analyze the waveform characteristics of the radar profiles in the non-dispersion and dispersion media and effectively guided the precise interpretation of radar data.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第4期1322-1334,共13页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(41074085)
教育部新世纪优秀人才支持计划(NCET-12-0551)
中南大学升华育英人才计划
湖南省普通高校青年骨干教师
湖湘青年创新创业平台培养对象项目共同资助
关键词
探地雷达
混合交替方向隐式有限差分法
亚网格技术
频散介质
正演模拟
Ground Penetrating Radar
Hybrid alternating direction iterative finite difference timedomain
Subgridding scheme
Dispersion media
Forward simulation
