Experimental and modelling study of creaming in concentrated emulsions under centrifugation

Abstract

Monitoring and modelling emulsion creaming/sedimentation is essential in several engineering applications. However, when dealing with concentrated emulsions, further challenges appear due to complex interactions that make their investigation tricky. In this study, we develop and validate a method that combines experiments and modelling to quantify the creaming kinetics in dense oil-in-water emulsions. Centrifugation is used to accelerate phase separation. Glycerol is added to the continuous phase to modify its refractive index, making it closer to that of the dispersed phase, which increases light transmission in concentrated emulsions and enables tracking of droplet creaming by light transmission measurements. A one-dimensional convection–diffusion model is evaluated against experimental data using various hindered-settling velocity correlations. Dimensionless analysis supports key modelling assumptions and elucidates the observed dynamics. Computational Fluid Dynamics simulations are also performed using the Euler–Euler method, and the results are compared to the experiments and the convection–diffusion model predictions.