Stability of Reactive Flows in Porous Media: Coupled Porosity and Viscosity Changes

The infiltration flow of a reactive fluid in a porous medium is investigated. The reaction causes porosity/permeability changes in the porous medium as well as viscosity changes in the fluid. The coupling of the associated reaction-infiltration and Saflman-Taylor instabilities are considered. A mathematical model for this phenomenon is given in the form of a moving free-boundary problem. The morphological instability of a planar dissolution front is demonstrated using a linear stability analysis. An unexpected simplification occurs in that the resulting fourth-order equation can be solved explicitly.