Soft Matter and Complex Systems Seminar

Alteration of a rock composition can be caused by external fluids, which infiltrate the rock and dissolve some of its minerals. The dissolution does not proceed uniformly in the whole volume of the rock. Instead, a dissolution front forms, which is a quasi-2D surface between the altered (dissolved) and unaltered parts of the rock. All the chemical activity concentrates in the vicinity of the front. Linear stability analysis (LSA) of such a dissolution front was already studied in the 1980s. It was shown that whenever the altered rock is more permeable than the primary rock, a flat dissolution front is unstable and spontaneously breaks up into an array of protrusions. The characteristic distance between these protrusions was predicted. The further evolution of the system is dominated by strong nonlinear couplings between the fluid flow, reactant transport, and the porous matrix evolution. Therefore it was mostly studied by numerical simulations, and apart from the LSA, very few strict analytical results were obtained. In our research we aim to fill a part of this gap. We derive a weakly nonlinear theory of reactive infiltration, which goes one step further than the traditional LSA. Analyzing nonlinear couplings between two most important harmonic modes of the front perturbation, we study the first effects of nonlinearities: competition between the protrusions, and a symmetry breakup between the leading and the trailing parts of the dissolution front. We estimate the moment when the linear description of the process becomes inappropriate.