Reactive mass transport modeling in discretely-fractures porous media
Ghogomu N.F. et Therrien R.
This paper presents a model that simulates groundwater flow and multispecies transport in discretely-fractured porous media. The porous matrix is discretized with three-dimensional elements, and discrete fractures are represented by two-dimensional planar elements. Superposition of fracture and matrix nodes ensures fluid and mass continuity. Advective-dispersive transport is coupled with reactive transport for chemical species that undergo either chemical equilibrium or kinetic reactions. The chemical system is defined mathematically with the law of mass action applied to each chemical reaction, and the mass conservation law to each basic chemical component. The resulting nonlinear algebraic system of equation is solved with the Newton-Raphson technique, and a sequential iterative approach couples the physical and chemical transport equations. A verification example involving simple mineral dissolution is presented. A second example with precipitation and dissolution of minerals illustrates the influence of discrete fractures and matrix diffusion on the spatial distribution of reactive chemical species.