Hydrodynamic acoustic absorption at the fluid/solid transition of suspensions

Abstract

A theoretical calculation of the excess acoustic attenuation due to hydrodynamic interactions in colloidal suspensions, when the suspended particles are spheres or plates, is presented. Our model is based on the fluid flow shearing between suspended particles during the passage of a longitudinal acoustic wave. To incorporate the many-body effects of the system, the nearest-neighbor distribution function for finite-size particles is introduced. The results of the modeling are compared to available experimental results. The main features of the experimental curves (e.g., attenuation maxima as a function of concentration and an increase in attenuation with frequency) are reproduced and it is shown that the attenuation due to hydrodynamic effects is a significant contribution to wave damping in high-concentration suspensions.