PNNL

Abstract

Many subsurface flow and transport problems of importance today involve coupled non-linear flow, transport, and reactions in media exhibiting complex heterogeneity. In particular, problems involving biological mediation of reactions fall into this class of problems. Recent experimental research has revealed important details about the physical, chemical, and biological mechanisms involved in these processes at a variety of scales ranging from molecular to laboratory scales. We are developing a hybrid multiscale modeling framework that combines discrete pore-scale models (which explicitly represent the geometry of grains and pores at a local scale) with continuum field-scale models (which conceptualize flow and transport in a porous medium without explicit pores and grains). At the pore scale, we have implemented a parallel three-dimensional Lagrangian model of flow and transport using the Smoothed Particle Hydrodynamics (SPH) method and performed test simulations using millions of computational particles on the supercomputer at the Environmental Molecular Sciences Laboratory (EMSL). We have also developed methods for gridding arbitrarily complex pore geometries and solution of pore-scale flow and transport using parallel implementations of grid-based computational fluid dynamics (CFD) methods. Within the multiscale hybrid framework, we have coupled pore- and continuum-scale models to simulate coupled diffusive mixing, reaction, and mineral precipitation, and compared the results with conventional continuum-only simulations. The hybrid multiscale modeling framework is being developed using a number of SciDAC enabling technologies including the Common Component Architecture (CCA), advanced solvers, grid technologies, scientific workflow tools, and visualization technologies.