Abstract

We investigate both experimentally and theoretically the influence of chemical reactions on the properties of buoyancy-driven convective fingering arising when two miscible or partially miscible liquids are put in contact in the gravity field in a porous medium or Hele-Shaw cell. We show that, in the case of miscible liquids, a chemical reaction can break the symmetry of the fingering patterns as fingers can develop on one side of the contact line only and not both up and downwards as in the non reactive situation. In some cases, the dynamical in-situ generation of the product of the reaction can even lead to the co-existence of different convective modes. The experiments are performed using an aqueous solution of an acid put in contact in a Hele-Shaw cell with a miscible aqueous solution of a base. The numerical simulations are made on the basis of a reaction-diffusion-convection model coupling Darcy’s law to the evolution equations of the concentrations of the various chemicals involved. Good agreement between experimental results and theory is obtained. In the case of partially miscible liquids, we show that chemical reactions are also able to control the fingering pattern.