Multiple wave scattering in soft complex media #

Valerie J Pinfield

14:50 Tuesday in 4Q05.

Part of the Multiple wave scattering session.

Abstract #

Multiple scattering of ultrasonic waves in soft complex media such as colloidal particle suspensions can be modelled in the long wavelength regime by use of multipole expansions and the T-matrix for the scattering of an individual scatterer, and ensemble averaged multiple scattering formulations. These result in an effective wavenumber for the propagation which in many cases agrees well with experimental measurements. However, there are a number of complexities to consider in these systems, including the presence of non-identical scatterers, for example where there is a distribution of particle size or a mixture of several dispersed components. In addition, multiple wave modes are generated in the continuous phase by scattering at the particles, and these influence the multiply-scattered field and create interesting dependence of the effective wavenumber even in the Rayleigh regime. Here, we examine the mathematical models for some of these effects and their implications for ultrasound propagation properties in typical physical systems.