Estudo Numérico da dissolução do CO2 em aquíferos salinos com interface deformada

Abstract

We address the problem of buoyancy-driven fingering generated in porous media by the instability of a partially miscible fluid layer dissolving in a less dense fluid existing underneath. The fingering process induces an uneven distribution of dissolved CO2 in the upper layers, which affects the surface tension distribution at the interface, and unstabilizes the geometry of the flat surface. We assume a curved interface to model surface tension effects. The main purpose is to check if the curved surface increases the CO2 dissolution rate and a evaluate a curvature that maximizes the gas dissolution. A 2D time dependent numerical simulation is performed, assuming that the flow is governed by Darcy s law, along with the Boussinesq approximation, to account for buoyancy effects introduced by concentration dependent densities. The results show that the interface deformation induces the onset of fingering, however the number of fingers decreases as the deformation increases and the dissolution rate is influenced by the prescribed interface deformations. The velocity field is modeled by a vorticity-stream function formulation. The resulting equations are solved through the Taylor-Galerkin Finite Element Method, using a Crank-Nicolson time discretization.