Dispersed Turbulent Multiphase Flows

In geophysical suspensions internal stresses arise from the interaction between the fluid and solid particles. The characteristics of the stresses reflect the main features of the particles, namely the size, the shape and the density. While particles in the micron and sub-micron scales exhibit dynamics which depend on the thermal agitation of the fluid phase (e.g. Brownian motions) and possibly on the presence of dissolved ions (e.g. electrokinetic phenomena), the dynamics of particles larger than \(\mathcal {O}(10)~\upmu \) m, namely non-Brownian particles, are driven by viscous and convective interactions with the fluid and by inter-particle contacts. Most of geophysical flows are turbulent and it is legitimate to wonder (i) what is the effect of turbulence vortices on the particle motion and (ii) whether the presence of particles may affect the turbulence properties. In this chapter, the questions (i) and (ii) are discussed for non-Brownian sediment particles.