Acoustic Scattering Models from Rough Surfaces: A Brief Review and Recent Advances

Abstract

This paper proposes a brief review of acoustic wave scattering models from rough surfaces. This review is intended to provide an up-to-date survey of the analytical approximate or semi-analytical methods that are encountered in acoustic scattering from random rough surfaces. Thus, this review focuses only on the scattering of acoustic waves and does not deal with the transmission through a rough interface of waves within a solid material. The main used approximations are classified here into two types: the two historical approximations (Kirchhoff approximation and the perturbation theory) and some sound propagation models more suitable for grazing observation angles on rough surfaces, such as the small slope approximation, the integral equation method and the parabolic equation. The use of the existing approximations in the scientific literature and their validity are highlighted. Rough surfaces with Gaussian height distribution are usually considered in the models hypotheses. Rather few comparisons between models and measurements have been found in the literature. Some new criteria have been recently determined for the validity of the Kirchhoff approximation, which is one of the most used models, owing to its implementation simplicity.

Towards Explainable Augmented Intelligence (AI) for Crack Characterization

“…The set-up is more than the one used in the DPS experiments: both the top surface and blackwall are more indulated and there is a backwall breaking flaw, creating additional response, see Figures 15b and 16a. The numerical experiments conducted with CIVA [22] (a commercial package for analyzing and simulating NDT [23][24][25][26][27][28], in particular, NDT of components with irregular surfaces [7,8,28,29]) showed that the notch fabricated for the purposes of this experiment was best imaged using the half-skip LTT mode, with the L (longitudinal) transmitted signal converting at the backwall to the T (transverse) and then reflecting from the notch, so that the received signal is also T, see Figure 16a. The set-up is more challenging than the one used in the DPS experiments: both the top surface and blackwall are more indulated and there is a backwall breaking flaw, creating additional response, see Figures 15b and 16a.…”

The effect of 3D surface roughness on acoustic wave propagation in a cylindrical waveguide

“…Other related methods e.g. small slope approximation [8] and parabolic equation [9], are reviewed by more recent authors [10,11].…”

Correspondence between reflected and incident pulse signals on acoustic diffuse surfaces

“…reflectance), the ratio between the reflected and the incident energy. Since the characterization of scattering is not so simple [2], researches continue to be conducted in order to experimentally evaluate the sound reflection from diffuse surfaces. Recently, investigations on the sound reflection from corrugated diffuse surfaces have been done with a twomicrophone method [3].…”