The flow of suspensions

Abstract Most rheological and rheo‐optical properties of suspensions such as viscosity and light‐scattering intensities can be expressed in terms of the average orientation and/or the average concentration distribution of the suspended particles. In general one can distinguish several distinct regimes: (i) infinitely dilute, (ii) dilute, (iii) semi‐dilute or moderately concentrated, and (iv) concentrated suspensions. Cases (i) and (ii) are regimes in which particle interactions are either absent or only two‐body interactions are important. These cases can, in general, be well described theoretically. Regime (iii) is characterized by n‐body (n ≥ 2) interactions and is the least understood. Regime (iv) can often be described in terms of a cell model in which the motion of a reference particle, or the fluid motion around it, is described.