Attenuation of sound in concentrated suspensions: theory and experiments

Ensemble-averaged equations are derived for small-amplitude acoustic wave p ropagation through non-dilute suspensions. The equations are closed by intr oducing effective properties of the suspension such as the compressibility, density, viscoelasticity, heat capacity, and conductivity. These effective properties are estimated as a function of frequency, particle volume fract ion, and physical properties of the individual phases using a self-consiste nt, effective-medium approximation. The theory is shown to be in excellent agreement with various rigorous analytical results accounting for multipart icle interactions. The theory is also shown to agree well with the experime ntal data on concentrated suspensions of small polystyrene particles in wat er obtained by Allegra & Hawley and for glass particles in water obtained i n the present study.