Design and application of flux corrected transport for reactive solute transport modeling

Understanding reactive solute transport, which couples flow , transport, and chemical/ biological reaction in porous media, is important in areas such as aquifer remediation, groundwater contamination and geochemical reaction modeling. Due to the large time scales involved, lack of accessibility to the subsurface and heterogeneous physical and chemical parameters, numerical simulation models are important and widely used in most of these studies. Conventional numerical methods to solve solute transport can produce non-physical values (negative concentrations) even for some simple cases when considering full tensor dispersion. Particularly when considering heterogeneous flow fields, irregular grids, nonlinear reactions and large time scales, the non-physical values can spread out to the whole domain and cause numerical convergence problems for reactive transport cases. Conventional finite element and finite difference methods to discretize full tensor dispersion may lead to non-physical solutions independent of the grid size; therefore, this problem cannot be ignored. The well-known Flux Corrected Transport (FCT)technique can be used to solve this problem. This methodology can produce a high-order, physical solution by combining a high-order solution (high accuracy, but non-physical) and a low-order solution (low accuracy, but positive) with a nonlinear flux limiter. The nonlinear flux limiter is an anti-diffusion component, which can diminish the artificial-dispersion from low-order method and hence improve the accuracy without producing a non-physical solution. In this study, the accuracy of Flux Corrected Transport is tested for different cases with complex flow fields and chemical reactions. We consider cases where accurate modeling of full tensor dispersion is required to simulate mixing-induced nonlinear reaction. The results indicate that FCT is a simple, flexible and accurate method to obtain positive solution for solute transport modeling.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2013

Author dc:creator

• Wang, Guoyin

Contributors dc:contributor

• Valocchi, Albert J.

• reactive transport
• flux corrected transport
• negative concentraions

Statement dc:rights

• Copyright 2013 Guoyin Wang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/45466

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/45466