Wave scattering by a two‐dimensional band‐limited fractal surface based on a perturbation of the Green’s function
作者:
P. E. McSharry,
P. J. Cullen,
D. Moroney,
期刊:
Journal of Applied Physics
(AIP Available online 1995)
卷期:
Volume 78,
issue 12
页码: 6940-6948
ISSN:0021-8979
年代: 1995
DOI:10.1063/1.360461
出版商: AIP
数据来源: AIP
摘要:
A fast approximate method is described to calculate the acoustic scattering from a one‐dimensional Dirichlet band‐limited fractal surface. The formulation is based on a perturbation of the Green’s function allowing an approximation of the propagator in the kernel of the Helmholtz integral equation, which reduces the integral equation to a convolution equation. This allows us to find a solution using Fourier transforms rather than the usual matrix inversion that is required. We have shown that in the limit of smallk&sgr;, wherekis the incident wave number and &sgr; is the rms height, it is possible to find accurate closed form expressions for the reflection coefficientsRn, the spectral components of the normal gradient of the field &psgr;n, the scattered fieldpsca, and the angular scattering coefficientIscarepresenting the scattering from a band‐limited fractal surface. For small values ofk&sgr;≪1, we have used the generalized Rayleigh method [D. L. Jaggard and X. Sun, J. Appl. Phys.68, 5456 (1990)] to determine the theoretical linear relationship which exists between the slope of the absolute value of the reflection coefficients in dB versus the reflection mode and the fractal dimensionD. This theoretical relationship has been verified by using the Green’s function perturbation method. This relationship and an analogous relationship between the scattering coefficient and the scattering angle allows the determination of the fractal dimensionDand the rms height &sgr; from the scattering pattern whenk&sgr;≤0.2. ©1995 American Institute of Physics.
点击下载:
PDF
(925KB)
返 回