Generic Reaction-Based BioGeoChemical Simulator (RBBGCS), Version 1.0

摘要

This report presents a generic reaction-based biogeochemical simulator (RBBGCS) that was developed as part of the advancement of the subsurface reactive transport capability in the Adaptive Hydrology/Hydraulics (ADH) model. RBBGCS has been incorporated into ADH to model subsurface reaction transport. The simulator can also be coupled with other transport models to perform reactive transport modeling in surface and subsurface systems. RBBGCS can model geochemical/biogeochemical reactions that are equilibrium controlled (fast reversible), instantaneous (fast irreversible), and kinetic (slow reversible or irreversible). It has a preprocessor that automatically and systematically produces reaction-based differential-algebraic equations (DAE) as the reaction governing equations and a solver that solves the set of governing equations for the concentration distribution of chemical species. It allows both userspecified empirical equation and formulation based on the collision theory to be used to describe reaction equilibrium and reaction rate(s). The numbers of chemical species, biogeochemical reactions, and porous medium phases that may be defined for a modeled system are unrestricted, limited only by the computational resources that are available.