Finite difference simulation and characteristics of seismic wave propagation in viscoelastic media under CPML boundary condition
YUE Youxi;ZHANG Huijuan;WEN Xue;LIU Bingqing;ZHAO Ying;LIU Chenxi;School of Geosciences,China University of Petroleum;Shenzhen Branch,CNOOC Ltd;
In numerical wave simulation of finite difference for wave equation,in order to make boundary wave field of computation approximate the true wave field value well,boundary condition has been used to minimize artificial reflection from the edges of the domain of computation by boundary condition. The classical split perfectly matched layers( SPML) absorbing boundary condition can not effectively absorb grazing wave. While,the improved unsplit convolutional perfectly matched layers( CPML) can efficiently tackled this problem,and the unphysical split of wave field is not necessary under CPML condition. In this paper,high-order staggered-grid finitedifference method has been used to simulate seismic waves of Kelvin-Voigt viscoelastic media,and meanwhile the unsplit convolutional perfectly matched layers( CPML) absorbing boundary condition is introduced into its boundary. Numerical simulation demonstrates that compared with elastic wave,low-frequencey grazing waves which generate at large incident have greater impact on viscoelastic wave. CPML absorbing boundary condition is better than SPML absorbing condition for the absorption of low-frequencey grazing waves.