Radiative transfer theory is used to model the multiple scattering of diffuse ultrasonic waves in two types of random media. The first type is an isotropic, homogeneous medium containing randomly oriented, randomly located scatterers. The scatterers are assumed to be uncorrelated. This assumption allows an equation of transfer to be written which governs the multiply scattered intensities. This ultrasonic radiative transfer equation (URTE) contains single scattering and propagation parameters that are calculated using the elastic wave equation. Polarization effects are included through the introduction of an elastodynamic Stokes vector which contains a longitudinal Stokes parameter and four shear Stokes parameters similar to the four Stokes parameters used in optical radiative transfer theory. The theory is applied to a statistically homogeneous isotropic half space containing randomly distributed spherical voids illuminated by a harmonic plane wave.
Applied Mechanics, Engineering, Materials Science, Physics, Acoustics
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign