Effective Stochastic Model For Reactive Transport

This chapter describes the Langevin advection-diffusion-reaction (LADR) model, an effective stochastic model defined on the scale L. For reactive transport, results show that the error in the Darcy advection-dispersion-reaction model increases with the decreasing dilution index. The error is defined as the ratio between masses of the reaction product obtained from the pore- and Darcy-scale simulations. The chapter then demonstrates that separate treatment of advective and diffusion mixing is more accurate for modeling multicomponent reactive transport. Pore-scale flow and transport equations are solved numerically using the smoothed particle hydrodynamics (SPH) method. Multicomponent reactive transport in porous media is a challenging problem because of the complex interplay between diffusive and advective mixing and reactions. In the case of the concentration-gradient-driven Rayleigh-Taylor instability, author's results show that the advection-dispersion model underestimates the concentration gradient across the front separating two miscible fluids and the rate of the Rayleigh-Taylor instability growth.