Modeling and verification of non-linear mineral dissolution processes with buoyancy effects

Abstract

A new methodology for the simulation of salt cavity development by dissolution is presented, verified and qualitatively validated by experiments. Starting from an initial cavity, the simulator models the injection of fresh water, natural and forced convection of the brine, and the evolution of the cavity walls due to dissolution. The nonlinear model couples brine mass and momentum conservation (governed by incompressible Navier–Stokes equations) with the buoyancy effect due to the brine density variations. Vortex generation and density-driven brine plume rise demonstrate the impact of complex brine flow patterns on the dissolution front evolution. A new explicit interface tracking strategy is employed to investigate the dissolution front movement and an improved smoothing algorithm to enhance the model robustness, contributing to low computational cost and stable simulation for the long-term dissolution process simulation. The proposed model is verified by conducting spatial and temporal convergence studies and qualitatively validated using lab-scale experiments. The agreement between experiments and simulations of horizontal and vertical dissolution cases demonstrates the utility of the model. The simulation results indicate that the rising plume of brine results in a “morning glory” shape cavity under a vertical dissolution scenario and a significant difference between upper and lower fronts dissolution rates for the horizontal dissolution case. The coupling effect of eddy development and cavity shape evolution is also discussed. This work furthers the understanding of the interaction between brine transport in an initially-formed cavity and dissolution patterns of the cavity boundaries, driven by gravity and convective flows.