科研之友
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摘要
It is of great significance to study the propagation law of high frequency electromagnetic wave of ground penetrating radar (GPR) in dispersive media through numerical simulation for improving the interpretation accuracy of observed data. Complex frequency shift perfectly matched layer (CFS-PML) has been widely used in finite difference time domain numerical simulation of GPR based on the first-order electromagnetic wave equation due to their superior absorption characteristics and its implementation methods involve the convolution calculation of electromagnetic fields and introduce many auxiliary variables, which reduce the computational efficiency. Therefore, starting from the Debye dispersive media electromagnetic wave equation in the complex stretch coordinate, this paper derives the non-splitting CFS-PML realization formulas of second order Debye dispersive media electromagnetic wave equation by constructing the auxiliary differential equation reasonably, which avoids the splitting and convolution calculation of electromagnetic wave field. On this basis, Galerkin method and Newmark-beta difference method are used to derive time domain finite element equation with non-splitting CFS-PML and its time difference discretization scheme. The simulated results of two GPR models demonstrate that the proposed non-splitting CFS-PML boundary condition implementation method based on auxiliary differential equations can effectively absorb the low frequency spurious reflected waves with large angle incidence and improve the simulation accuracy. Compared with non-dispersive media, the high frequency electromagnetic wave of GPR in dispersive media has stronger attenuation, longer wavelet duration, lower resolution and propagation velocity. These analysis results are helpful to improve the interpretation accuracy of observed GPR data.
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单位桂林理工大学
