Influence of initial plume shape on miscible porous media flows under density and viscosity contrasts

The effect of the initial condition upon the transport dynamics of miscible flowing fluids in a porous medium is investigated under viscosity and density contrasts. Such flows have attracted significant attention due to their importance in many fields of science and engineering, such as CO2 sequestration and aquifer remediation. Using high-resolution two-dimensional numerical simulations, we illustrate the impact of viscosity and density contrasts on the temporal evolution of the spreading and mixing quantities. We show that such impact depends on the initial shape of the source distribution where the solute is injected and on the intensity of the horizontal background flux. We find that rates of mixing are dependent on whether the solute is more or less viscous than the ambient fluid, a result usually not taken into consideration in studies on gravity fingering. At higher background flux, the effects due to horizontal viscous fingering dominate over gravitational fingering. Our computational analysis also suggests a non-trivial relationship between mixing and the length of the plume's interface under fingering instabilities. Finally, we show how a stratified permeability field can interact with these sources of instabilities and affect the transport behaviour of the plume.

Automated summary

The impact of viscosity and density contrasts on the transport dynamics of miscible flowing fluids in a porous medium under different initial conditions is investigated. The study shows that the initial shape of the source distribution and the intensity of the background flux have an influence on the temporal evolution of the spreading and mixing processes. It is found that the viscosity of the solute affects the rates of mixing, and the effects of horizontal viscous fingering dominate over gravitational fingering at higher background flux. The computational analysis also reveals a non-trivial relationship between mixing and the length of the plume's interface under fingering instabilities. Finally, the study demonstrates the interaction between a stratified permeability field and these instabilities, and how it affects the transport behavior of the plume.