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

reactive transport;flux corrected transport;negative concentraions

Wang, Guoyin ; Valocchi ; Albert J.

关键词: reactive transport;    flux corrected transport;    negative concentraions;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45466/Guoyin_Wang.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

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 tothe large time scales involved, lack of accessibility to the subsurfaceand heterogeneous physical and chemical parameters, numerical simulation modelsare important and widely used in most of these studies. Conventionalnumerical methods to solve solute transport can produce non-physicalvalues (negative concentrations) even for some simple cases when consideringfull tensor dispersion. Particularly when considering heterogeneousflow fields, irregular grids, nonlinear reactions and large time scales,the non-physical values can spread out to the whole domain and causenumerical 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 thisproblem. This methodology can produce a high-order, physical solutionby combining a high-order solution (high accuracy, but non-physical)and a low-order solution (low accuracy, but positive) with a nonlinearflux limiter. The nonlinear flux limiter is an anti-diffusion component,which can diminish the artificial-dispersion from low-order method and henceimprove the accuracy without producing a non-physical solution. In thisstudy, 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 solutetransport modeling.