UC Irvine

Calcium carbonate, which is an important mineral in both anthropogenic and biological sys- tems, is a very critical component in nature. Numerous studies have shown that precipitation of calcium carbonate in fractured and porous media influences solute transport. Previous studies have used two-dimensional computational models to mimic the three-dimensional fluid flow and reactive transport of dissolved mineral. With the goal of improving under- standing of mineral precipitation and transport process and to test the accuracy of results from the two-dimensional models, a three-dimensional, two-step reactive transport computa- tional model is developed with OpenFOAM, an open source, C++ based CFD toolbox. This thesis presents the processes of customizing OpenFOAM to solve reactive flow and transport in a three-dimensional variable aperture fracture. Several parameters, including resolution in aperture height direction, aperture fields, and relative roughness of fracture surfaces, are modified to assess sources of errors and to test the soundness of the model. Results are then directly compared with those from the two-dimensional model. Also, a comparison view of different discretization schemes for representing advection in the transport model is presented. All together, our research results suggest that even though false diffusion is observed, the upwind scheme is chosen because of its boundedness and stability.