Introduction and Theoretical Principles

The prevention of creaming in emulsions is an important aspect of commercial product formulation. In this section we discuss the theoretical aspects of droplets moving under gravity, and introduce a modification to the simple theory to allow for the effect of back-flow in concentrated emulsions creaming in a closed container. 

The creaming velocity, Us, of a spherical droplet in an infinite fluid medium is given by Stokes law  

The effects of droplet concentration on the creaming rate are well documented. 

Carter et alP have attempted to allow for the effects of concentrated dispersions by using an effective viscosity in place of the medium viscosity, rj, in eqn. (4.1). They chose the theoretical mean-field viscosity, /br, of a concentrated dispersion of non-interacting hard spheres given by Ball and Richmond  

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