A smoothed particle hydrodynamics model for reactive transport and mineral precipitation in porous and fractured porous media

Abstract

A numerical model based on smoothed particle hydrodynamics (SPH) was used to simulate reactive transport and mineral precipitation in porous and fractured porous media. The stability and numerical accuracy of the SPH-based model was verified by comparing its results with analytical results and finite element numerical solutions. The numerical stability of the model was also verified by performing simulations with different time steps and different number of particles (different resolutions). The model was used to study the effects of the Damkohler and Peclet numbers and pore-scale heterogeneity on reactive transport and the character of mineral precipitation and to estimate effective reaction coefficients and mass transfer coefficients. Depending on the combination of Damkohler and Peclet numbers the precipitation may be uniform throughout the porous domain or concentrated mainly at the boundaries where the solute is injected and along preferential flow paths. The effective reaction rate coefficient and mass transfer coefficient exhibited hysteretic behavior during the precipitation process as a result of changing pore geometry and solute distribution. The changes in porosity and fluid fluxes resulting from mineral precipitation were also investigated. It was found that the reduction in the fluid flux increases with increasing Damkohler number for any particular reduction in the porosity. The simulation results show that the SPH, Lagrangian particle method is an effective tool for studying pore-scale flow and transport. The particle nature of SPH models allows complex physical processes such as diffusion, reaction, and mineral precipitation to be modeled with relative ease. Copyright 2007 by the American Geophysical Union.