Gravitational instability and its scaling relation of a partially miscible two‐component system in a porous medium

Abstract

In the context of the co-injection of CO2 and impurities, such as H2S, SOx and N2, in the carbon capture and geological sequestration, the effect of the double diffusion on the onset and the growth of buoyancy-driven convection are studied theoretically and numerically. Based on the density profile, asymptotic stability limits are suggested as a function of the diffusivity ratio, δB, and the buoyancy ratio, −rβrC. In order to obtain more accurate features of the stability characteristics, the linear stability analysis and the nonlinear numerical simulations are also conducted. It is interesting that the present asymptotic, linear and nonlinear analyses are in good agreement. Based on the present stability analyses, we tried to find out the scaling relations which can be used as control parameters in related systems. In the double diffusive (DD) convection and the extended double diffusive (EDD) convection regimes, a new scaling relation is suggested by the temporal change of the density gradient rather than the density difference or the density gradient.