Fast compressional wave attenuation and dispersion due to conversion scattering into slow shear waves in randomly heterogeneous porous media.
Fast compressional wave attenuation and dispersion due to conversion scattering into slow shear waves in randomly heterogeneous porous media.
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DOI：
10.1121/1.3560918
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
Tobias Malte Müller;P. Sahay
中科院分区：
文献类型：
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作者：
Tobias Malte Müller;P. Sahay
在波在多孔介质中传播的黏度扩展的Biot框架内，预测了一种速度不消失的慢横波模式的存在。这是一种高度扩散的剪切模式，其中两个组成相本质上经历了相外剪切运动（慢剪切波）。为了阐明这种波型与非均匀介质中传播波场的相互作用，采用统计平滑方法分析了随机非均匀孔隙弹性介质中快速纵波向慢横波的转换散射过程。结果得到了在动力等效均匀介质中传播的相干平面纵波的复波数。分析结果表明，转换散射过程从传播波中吸收能量，从而导致衰减和相速度色散。衰减和色散特征是松弛过程的典型特征，在这种情况下是剪切应力松弛。在宏观均质多孔弹性固体中，从黏性主导状态向惯性状态转变过程中，黏性边界层的形成与散射向慢横波的转换机制有关。
Within the viscosity-extended Biot framework of wave propagation in porous media, the existence of a slow shear wave mode with non-vanishing velocity is predicted. It is a highly diffusive shear mode wherein the two constituent phases essentially undergo out-of-phase shear motions (slow shear wave). In order to elucidate the interaction of this wave mode with propagating wave fields in an inhomogeneous medium the process of conversion scattering from fast compressional waves into slow shear waves is analyzed using the method of statistical smoothing in randomly heterogeneous poroelastic media. The result is a complex wave number of a coherent plane compressional wave propagating in a dynamic-equivalent homogeneous medium. Analysis of the results shows that the conversion scattering process draws energy from the propagating wave and therefore leads to attenuation and phase velocity dispersion. Attenuation and dispersion characteristics are typical for a relaxation process, in this case shear stress relaxation. The mechanism of conversion scattering into the slow shear wave is associated with the development of viscous boundary layers in the transition from the viscosity-dominated to inertial regime in a macroscopically homogeneous poroelastic solid.