Numerical simulations of reversible reactive flows in homogeneous porous media

The effects of reversibility on the viscous fingering of miscible reactive flow displacements in homogeneous porous media are examined through numerical simulations. A model in which the viscosities mismatch between the reactants and the chemical product triggers the instability is adopted. The problem is governed by the continuity equation, Darcy's law, and the convection-diffusion- reaction equations, which are solved using a pseudo-spectral method. It was found that in general, chemical reversibility tends to attenuate the instability at the fronts, resulting in less complex fingers than in the nonreversible case. However, stronger chemical reversibility also leads to less diffuse and thinner finger structures. Furthermore, the chemical product was found to be homogeneously distributed in the porous medium in the case of the reversible reaction, while strong concentration gradients are observed in the nonreversible case. The study has also revealed that chemical reversibility is capable of enhancing the instability of a stable reactive front. It is also found that the rate of production can be the same for different cases of frontal instability for a period of time that increases with the increase in the magnitude of chemical reversibility.