Steady-State Dilution and Mixing-Controlled Reactions in Three-Dimensional Heterogeneous Porous

三维多相多孔材料中的稳态稀释和混合控制反应

• 批准号: 217872108
• 负责人: Professor Dr.-Ing. Olaf A. Cirpka
• 金额: --
• 依托单位: Institut für Angewandte Geowissenschaften (IAG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/217872108?language=en
• 关键词: Steady; State; Dilution; Mixing; Controlled

Understanding transport of contaminants is fundamental for the management of groundwater re-sources and the implementation of remedial strategies. In particular, mixing processes in saturated porous media play a pivotal role in determining the fate and transport of chemicals released in the subsurface. In fact, many abiotic and biological reactions in contaminated aquifers are limited by the availability of reaction partners. Under steady-state flow and transport conditions, dissolved reactants come into contact only through transverse mixing. In homogeneous porous media, transverse mixing is determined by diffusion and pore-scale dispersion, while in heterogeneous formations these local mixing processes are enhanced. Recent studies investigated the enhancement of transverse mixing due to the presence of heterogeneities in two-dimensional systems. Here, mixing enhancement can solely be attributed to flow focusing within high-permeability inclusions. In the proposed work, we will investigate mixing processes in three dimensions using high-resolution laboratory bench-scale exper-iments and advanced modeling techniques. The objective of the proposed research is to quantitatively assess how 3-D heterogeneity and anisotropy of hydraulic conductivity affect mixing processes via (i) flow focusing and de-focusing, (ii) increase of the plume surface, (iii) twisting and intertwining of streamlines and (iv) compound-specific diffusive/dispersive properties of the solute species undergoing transport. The results of the experimental and modeling investigation will allow us to identify effective large-scale parameters useful for a correct description of conservative and reactive mixing at field scales allowing to explain discrepancies between field observations, bench-scale experiments and current stochastic theory.

了解污染物的运移对于地下水资源的管理和补救战略的实施至关重要。特别是，饱和多孔介质中的混合过程在决定地下释放的化学物质的去向和运输方面发挥着关键作用。事实上，受污染含水层中的许多非生物和生物反应受到反应伙伴可获得性的限制。在稳态流动和输送条件下，溶解的反应物只有通过横向混合才能接触。在均质多孔介质中，横向混合由扩散和孔隙尺度弥散决定，而在非均质地层中，这些局部混合过程被加强。最近的研究发现，在二维系统中，由于非均质的存在，横向混合的增强。在这里，混合增强可以完全归因于高渗透性包裹体内的流动聚焦。在这项拟议的工作中，我们将使用高分辨率的实验室台架实验和先进的建模技术来研究三维混合过程。这项研究的目的是定量评估水力传导性的三维非均质性和各向异性如何通过(I)流动聚焦和去聚焦，(Ii)羽流表面的增加，(Iii)流线的扭曲和缠绕，以及(Iv)正在传输的溶质物种的化合物特有的扩散/弥散特性来影响混合过程。实验和模拟研究的结果将使我们能够确定有效的大尺度参数，有助于正确描述现场尺度上的保守和反应混合，从而解释现场观测、台架实验和当前随机理论之间的差异。