Application of CFS-PML to finite difference time domain method in ground penetrating radar simulation

In order to eliminate the artificial reflected waves on truncation boundary,the boundary condition should be exerted in ground penetrating radar(GPR)numerical simulation.At present,perfectly matched layer(PML)boundary condition which is widely used has not good absorption effect on evanescent wave,low frequency wave and grazing angle wave.Thus,the complex frequency shifted convolution perfectly matched layer(CFS-PML)is introduced.From the Maxwell′s equations of two-dimensional TM wave,the principles of CFS-PML boundary condition are elaborated and its discrete difference formulas are deduced;then,the parameter selection principles of CFS-PML boundary condition are provided.By GPR wave field snapshot in homogeneous medium,the strength of the reflected wave of the truncation with no boundary condition and adding other three different boundary conditions are compared,and the results show that uniaxial anisotropic perfectly matched layer(UPML)and CFS-PML boundary conditions have better absorption effects.In order to further analyze the absorption effects of UPML and CFS-PML,the double medium long and narrow model is constructed.Through the wave field snapshots and global reflection error,it is proved that CFS-PML has better absorption effect on evanescent wave,low frequency wave and grazing angle wave than that of UPML.