Article révisé par les pairs
Résumé : Convection can develop upon dissolution of a given species A in a host phase when dissolution leads to a buoyantly unstable density stratification. If A reacts with a solute B present in the host solution according to a bimolecular A+B→C reaction, convective dissolution can be enhanced or slowed down depending on the relative contribution to density of each chemical species. We study numerically the influence of differential diffusion on such reactive convective dissolution in the nonlinear regime. In particular we compute the temporal evolution of the dissolution flux, its asymptotic value and the onset time of convection as a function of the ratio of the diffusion coefficients. We find that, when B diffuses faster than C, the density profiles can exhibit a local minimum below the reaction front where a double-diffusive instability develops. This has a destabilizing effect and leads to enhanced mixing, earlier onset of convection, and increased asymptotic fluxes. On the other hand, when B diffuses slower than C, the density profiles can contain a local minimum at the reaction front followed by a local maximum below, which gives rise to two convection zones with a diffusive-layer convection instability occurring below the reaction front. The overall dynamics is stabilizing with delayed onset of convection and with smaller asymptotic fluxes. When B and C diffuse at an equal rate but differently from A, differential diffusion can accelerate or slow down convection.