NUMERICAL-SIMULATION OF THE 2ND-ORDER KIRCHHOFF APPROXIMATION FROM VERY ROUGH SURFACES AND A STUDY OF BACKSCATTERING ENHANCEMENT

A Monte Carlo simulation is used to study the second-order Kirchhoff scattering and backscattering enhancement of a scalar wave from one-dimensional soft Gaussian rough surfaces. The surfaces are very rough with the rms height σ/λ = 0.707, 0.5, and 0.3, and the correlation distance l /λ = 1. Numerical results of the scattered intensity using the Kirchhoff approximation and second-order scattering are compared with the exact calculations of the integral equation. With the corrections of incident and scattering shadowing and the propagation shadowing for the second-order scattering, good agreement between approximate and exact results is obtained. The results also show that the backscattering enhancement may be explained by the second-order Kirchhoff scattering including shadowing effects. The law of energy conservation and the problem of convergence in the simulation are also investigated. The results of numerical simulation may be useful for the development of an analytical model for very rough scattering. © 1990, Acoustical Society of America. All rights reserved.