Ultrasound Propagation in Concentrated Suspensions: Shear-mediated Contributions to Multiple Scattering

We report analytical and numerical results of a multiple scattering model applied to silica-in-water suspensions. We investigate the shear-mediated effects due to mode conversion between compressional and shear wave modes, not included in standard multiple scattering models. We identify the dominant scattering contributions and develop analytical forms for them. Numerical calculations demonstrate the contribution of the additional shear-mediated effects to the compressional wave speed and attenuation through the suspension. As concentration is increased, we incorporate third order terms in concentration to the expansion of the effective wavenumber of the compressional wave. The calculations are compared with previously published experimental data.