A MODEL FOR SOUND-PROPAGATION IN A SUSPENSION OF SOLID PARTICLES

A modified version of the Kirchhoff-Stokes attenuation coefficient and a change of the wave speed are calculated for a dilute suspension of solid particles in a Newtonian fluid. The origin of the modification of the attenuation coefficient comes from the action of the Stokes drag force on the particles, which accounts for the interaction between the two phases, the fluid and the particles. In our model, the drag force is given only by its low-frequency expression and our results, therefore, are restricted to this regime. The temperature and the pressure are considered to be the same for both phases, and the equation of state for the fluid is arbitrary. The fluid is considered to have both shear and bulk viscosities, and thermal conductivity. The calculation is done within the framework of irreversible thermodynamics for a dilute biphasic system; further, an example is given which shows that, depending on the frequency, the attenuation coming from the particles may overwhelm the viscous one.