An improved numerical model of the vaulted tunnel is proposed in this paper,which of the radian can be changed from zero toπ/2.The tunnel can be seen as a waveguide approximately,and is excited by propagation model such as TE10,TM11,etc.In order to improve the effectiveness of the absorbing boundary condition(ABC),a perfectly matched layer(PML)medium with complex frequency-shifted(CFS)constitutive parameters is introduced for this study.The absorbing boundary is implemented by using the convolution PML(CPML...