Rough Surface Scattering and the Kirchhoff Approximation
Most approximate solutions to surface scattering begin with the Kirchhoff approximation to the unknown surface field. The validity of the Kirchhoff approximation is tested in this paper by the use of exact solutions for scattering from a pressure release sinusoid. Rough surfaces are expressed in a Fourier Series, and series solutions for small Rayleigh parameter are derived. The first order series term of Holford, Uretsky and Rayleigh are shown to be identical. Surface radiation patterns for shallow grazing angles are examined and conclusions are drawn on the region of validity of the Kirchhoff approximation.
KeywordsSurface Scattering Periodic Surface Kirchhoff Approximation Rough Surface Scattering Wave Height Spectrum
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