CAREER: Revisiting Two Basic Processes in Hydrogeology -- Solute Transport in Heterogeneous Formations and Chemical Mixing in Porous Media

建议的研究将重新考虑水文地质学中的两个基本过程：溶质在具有非均匀水力导电性的地层中的运移，以及多孔介质中的化学混合和反应。该教育计划将包括建立新的课堂工具，将物理模型与数值模拟相结合，并开发将研究生教育与当地水文地质问题相结合的项目。什么时候空间可变的水力传导性会导致分散，什么时候会导致非平衡传质？水文地质学家和土壤科学家发现，渗透率的空间异质性强烈地影响着地下水中溶质的运移。研究人员分为两大思想流派。第一种方法模拟了非均质作为传质（或双重孔隙）过程的影响，并将不动区大小参数化。第二种方法将非均质性对输运的影响建模为色散过程，通常是菲克过程，并将有效（或宏观）色散系数与渗透率场的空间统计量联系起来。我们将进行实验和理论研究，以确定每种模型适用的条件。特别是，我们将研究引起扩散传质的空间结构类型。化学物质如何与多孔介质混合和反应？在多孔介质中建立准确的反应模型取决于分子在反应之前相遇的方式，机械分散和化学混合（或孔隙尺度混合）可能不是同义词。例如，机械分散的部分原因可能是溶质通过某些孔隙而不是通过邻近的孔隙。结合物理演示和数值模拟。通过在课堂上同时使用物理模型和数值模型，学生可以理解自然过程和数学模型之间的联系（和差异）。这种结合使学生深入了解概念/数学模型与物理现实的关系。两者将通过使用LCD投影仪连接起来，将数值传输模拟的视觉输出直接显示在演示罐中，叠加模拟和真实的染料羽流。整合水文地质学和政策。学生将参与一个为当地社区提供环境和水文专业知识的非营利组织，参与当地的水文问题。

9875995HarveyThe proposed research will reconsider two basic processes in hydrogeology: Solute transport through formations with heterogeneous hydraulic conductivity, and chemical mixing and reaction in porous media. The educational initiative will consist of building new classroom tools that combine physical models with numerical simulation, and developing projects that integrate graduate education with local hydrogeologic issues.When does spatially variable hydraulic conductivty cause dispersion and when does it cause nonequilibrium mass transfer? Hydrogeologists and soil scientists have found that spatial heterogeneity in permeability strongly influences the transport of solutes in groundwater. Researchers are divided between two principal schools of thought. The first models the effects of heterogeneity as a mass-transfer (or dual-porosity) process, and parameterizes the size of immobile zones. The second models the effects based on heterogeneity on transport as a dispersive, usually Fickian, process and relates an effective (or macro) dispersion coefficient to the spatial statistics of the permeability field. We will conduct experimental and theoretical research to determine the conditions under which each model is appropriate. In particular, we will investigate the type of spatial structures that give rise to diffusive mass transfer.How do chemicals mix and react to porous media? Developing accurate models of reaction in porous media hinges on accounting for the way molecules meet each other before they can react, and mechanical dispersion and chemical mixing (or pore-scale mixing) may not be synonymous. For example, mechanical dispersion may result, in part, from solute movement through some pores, but not through adjacent pores.Combining physical demonstrations and numerical modeling. Students gain understanding of the connection (and differences) between natural processes and mathematical models by using physical models simultaneously with numerical models in the classroom. The combination gives students insight into the relation of conceptual/mathematical models and physical reality. The two will be joined by using an LCD projector to display the visual output of a numerical transport simulation directly onto a demonstration tank, superimposing the simulated and real dye plumes. Integrating hydrogeology and policy. Students will be engaged in local hydrologic issues by involvement in a nonprofit organization that provides environmental and hydrologic expertise for local communities.