Smoothed boundary conditions, coherent low‐frequency scatter, and boundary modes
Smoothed boundary conditions, coherent low‐frequency scatter, and boundary modes
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平滑边界条件、相干低频散射和边界模式
DOI：
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发表时间：
1984
期刊：
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通讯作者：
I. Tolstoy
中科院分区：
文献类型：
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作者：
I. Tolstoy
粗糙表面的低频相干散射可以方便地使用应用于光滑表面的线性边界条件来研究，其形式为φs/φ z=ηφ，其中φ，φs分别是代表总场势和散射场势的波动方程的解。这里讨论的理论的有效性仅限于kh 1，其中k是波数，h是粗糙元素之间的平均间距。常数η是频率、入射角和粗糙度类型的函数;在散射体各向同性分布在两种流体之间的界面上的一般情况下，它对八个物理参数敏感。讨论了各种粗糙边界的η的计算方法，并对凸台模型和随机扰动模型进行了比较。还检查了光滑边界条件的有趣含义;例如，边界波是一种真实的传播模式，它对应于在边界附近捕获的能量。
Low‐frequency coherent scatter from a rough surface may be conveniently investigated using a linear boundary condition applied to a smoothed surface, of the form ∂φs/∂z=ηφ, where φ, φs are solutions of the wave equation representing, respectively, the total and scattered field potentials. The validity of the theories discussed here is restricted to kh≲1, where k is the wavenumber and h the mean spacing between roughness elements. The constant η is a function of frequency, angle of incidence, and type of roughness; in the general case of scatterers distributed isotropically over an interface between two fluids it is sensitive to eight physical parameters. Methods of calculating η for various types of rough boundary are discussed, and comparisons are made—notably between the boss and the stochastic perturbation models. Also examined are interesting implications of the smoothed boundary conditions; e.g., the boundary wave which is a true propagating mode corresponding to energy trapped in the vicinity of a r...