弱不均一分散系における音響散乱の理論的解析

概要

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A unified theory on the scattering from weakly inhomogeneous dispersive media at high volumetric concentration of dispersed materials is introduced in this presentation. This problem which seems rather simple is certainly important in the understanding of the acoustic structure of biological tissue for recent approaches to tissue characterization with ultrasound. This paper describes the derivation of scattering intensity of acoustical waves from the weakly inhomogeneous dispersive medium under the conditions of long wave incidence and far-field observation from the viewpoint of statistical continuum theory. 1) Effective physical constants of the dispersive medium, such as adiabatic compressibility ; κ and spatial density ; γ are strictly defined by assuming statistical continuity of the space, and the general formula of wave equation for weakly inhomogeneous medium is derived. 2) Secondary wave from the spatial fluctuations of acoustical constants around their effective values is derived for primal incidence of plane wave by using the method of small perturbation, which is called Born Approximation. 3) The 2-point correlation function of random aggregates of monodisperse spheres is proposed as a modification of Debye's formulation. 4) Differential scattering cross section per unit sample volume is calculated for the evaluation of the averaged scattering intensity.
社団法人日本音響学会の論文
1980-10-01