Miscible viscous fingering: Experiments versus continuum approach

Abstract

The growth of viscous fingers inside three‐dimensional (3‐D) porous media is studied using an acoustic technique to determine the concentration profile. Three different porous media and a wide range of viscosity ratios and flow rates have been considered. The experimental data support the definition of an instability parameter that characterizes the essential features of the viscous fingering phenomenon. The dependence of this parameter on viscosity ratio, flow rate, and the nature of the medium is compared to theoretical predictions made using a continuum approach. The data demonstrate the predicted crossover between diffusive and linear growth, and the increase of the instability with heterogeneity. The enhancement of the growth rate due to the coupling between large viscosity ratio and velocity‐dependent hydrodynamic dispersion is also observed.