Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
In this study, the viscous fingering instability that develops daring the displacement of oil-in-water (0/W) emulsions by water is investigated. For this purpose, a horizontal rectilinear Hele-Shaw cell is used as an analogue for the porous media. The emulsions are prepared by dispersing a mineral oil in water using non-ionic surfactants. Different concentrations of oil were used to generate different emulsions that are characterized by examining their droplets size distribution and viscosity. The emulsions are displaced at different injection rates and the developments of the instability are characterized qualitatively by identifying the main mechanisms of finger development and growth. These results and the correlations between the properties of the fluids and the flow patterns are used to understand the flow dynamics and its effects on the viscous fingering instability. It is found that the development of the flow instability can be correlated with the rheological behaviour, which in tum depends on the emulsions' concentration and their internal microstructure.