Dissolution-driven convection of partially miscible fluids in porous media*

Dissolution-driven convection produced at a free interface~between~CO2 and~brine~in porous media is numerically studied to mimic the complex diffusion and flow process in the~geological sequestration of CO2. A Darcy-Cahn-Hilliard model~with~a particular~free energy distribution is employed to~simulate~the partially miscible feature~between the~CO2 and~the brine.~Simulations reveal that the evolution of the~CO2 plume~exhibitsseveral~distinct stages, such~as triggering, growing, merging and damping.~Consequently, for the temporal~development~of the solute flux~we can distinguish~three~major time periods, such as~free convection,~constrained convection and~shutdown. In the~free convection period, the time-averaged solute flux decreases with Rayleigh number.~On the other hand,~the solute flux is independent of the Rayleigh number~in the periods of constrained convection and~shutdown.~Correlations of the~solute flux~and the~Rayleigh~number are proposed based on the simulations, which are able to~predict the solute flux and the dissolved quantity of CO2 into brine.~~