The absorption of sound in emulsions and suspensions is due to viscous and thermal transport processes occurring at the interface of the nonhomogeneities, as well as to the intrinsic absorption in the materials comprising the system. For highly concentrated mixtures, multiple scattering is shown to play an important role. Following the arguments of Waterman and Truell [J. Math. Phys. 2, 512 (1961)], the behavior of the scattering medium may be specified explicitly in terms of the number of scatterers per unit volume, and the farfield amplitude f(O) obtained for a single scatterer. The coefficients of frO) for a single scatterer have been calculated by Allegra and Hawley [J. Acoust. Soc. Am. 51, 1545 (1972)] for systems of solid and fluid particles suspended in a fluid media. PACS numbers: 43.35.Bf, 43.85.Dj, 43.20. Hq LIST OF SYMBOLS A ae, as, at Cv, C• c c! f P P.(cosO), Pn=(cosO) R t T shear-wave potential radius of particle times the wave number of the compressional, shear, and thermal waves, respectively specific heats speed of sound for longitudinal compressional wave speed of sound for spherical compressional wave in elastic isotopic solid frequency of sound wave farfield amplitudes spherical vessel functions wavenumbers of compressional, shear, and thermal wave pressure viscous stress tensor Legendre polynomials, associated Legendre polynomials radial coordinate radius of suspended particle time temperature specific internal energy v e Ol L y =C,/Cv P (• = kp/Cp velocity of volume element real part of a s attenuation coefficient attenuation in pure liquid thermal dilatation ratio of specific heats kronecker symbol volume fraction of particulate material equal to concentration coefficient of shear rigidity polar angie thermal conductivity, complex wave propagation constant coefficient of shear viscosity kinematic viscosity density thermal diffusivity •b0, •bo •bt, •bs, •b, incident, compressional, thermal, shear, and reflected wave potentials •bE, ½s exciting and scattered wave function
