Kozak Joseph Alexander, Reeves Howard William, Lewis Barbara Ann
Department of Civil Engineering, McCormick School of Engineering and Applied Science, Northwestern University, 2145 North Sheridan Road, Evanston, IL 60208-3109, USA.
J Contam Hydrol. 2003 Nov;66(3-4):179-200. doi: 10.1016/S0169-7722(03)00032-9.
A one-dimensional flow and transport model was developed to describe the movement of two fluid phases, gas and water, within a porous medium and the transport of 226Ra and 222Rn within and between these two phases. Included in this model is the vegetative uptake of water and aqueous 226Ra and 222Rn that can be extracted from the soil via the transpiration stream. The mathematical model is formulated through a set of phase balance equations and a set of species balance equations. Mass exchange, sink terms and the dependence of physical properties upon phase composition couple the two sets of equations. Numerical solution of each set, with iteration between the sets, is carried out leading to a set-iterative compositional model. The Petrov-Galerkin finite element approach is used to allow for upstream weighting if required for a given simulation. Mass lumping improves solution convergence and stability behavior. The resulting numerical model was applied to four problems and was found to produce accurate, mass conservative solutions when compared to published experimental and numerical results and theoretical column experiments. Preliminary results suggest that the model can be used as an investigative tool to determine the feasibility of phytoremediating radium and radon-contaminated soil.
开发了一个一维流动与输运模型，用于描述多孔介质内气相和水相这两种流体相的运动，以及这两相内部和之间的镭 - 226和氡 - 222的输运。该模型还包括植物对水以及可通过蒸腾流从土壤中提取的水相镭 - 226和氡 - 222的吸收。数学模型通过一组相平衡方程和一组物种平衡方程来构建。质量交换、源汇项以及物理性质对相组成的依赖性将这两组方程耦合在一起。对每组方程进行数值求解，并在两组方程之间进行迭代，从而得到一个集迭代组成模型。如果给定模拟需要，采用彼得罗夫 - 伽辽金有限元方法以实现上游加权。质量集中法可改善解的收敛性和稳定性。将所得数值模型应用于四个问题，与已发表的实验和数值结果以及理论柱实验相比，发现该模型能产生准确的、质量守恒的解。初步结果表明，该模型可用作一种研究工具，以确定对受镭和氡污染土壤进行植物修复的可行性。
