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在地震波场数值模拟中,为了消除由人为边界产生的边界反射,需要引进边界吸收条件。本文从声波方程完全匹配层吸收边界的经典方法出发,基于高斯函数任意阶光滑的特点,提出了一种高斯型衰减因子,分析比较该因子与一般衰减因子的性质,并基于均匀与层状速度模型分别进行了数值模拟计算。数值结果显示,当选择相同的PML边界吸收层层数时,高斯型衰减因子的吸收效果明显优于一般的衰减因子,边界反射更少,信噪比更高;对比最近提出的正弦型衰减因子,在信噪比接近的情况下,高斯型衰减因子所需的PML吸收层层数更少。
In the numerical simulation of seismic wavefield, in order to eliminate the boundary reflection caused by the artificial boundary, it is necessary to introduce the boundary absorption condition. Based on the classical method of perfectly matched layer absorbing boundary of acoustic wave equation, this paper presents a Gaussian attenuation factor based on the characteristics of any order smoothness of Gaussian function. The properties of this factor and general attenuation factor are analyzed and compared. Based on the uniform and laminar velocity The models are respectively numerically simulated. The numerical results show that when the same PML boundary layer is selected, the absorption of Gaussian attenuation factor is obviously better than that of general attenuation factor, the boundary reflection is less and the signal-to-noise ratio is higher. Compared with the recently proposed sinusoidal attenuation factor , The Gaussian attenuation factor requires fewer layers of PML absorber at similar signal-to-noise ratios.