Collaborative Research: Fundamental Research on Oscillatory Flow in Hydrogeology

合作研究:水文地质学中振荡流动的基础研究斯坦福大学peter Kitanidis威斯康星大学michael Cardiff warren Barrash博伊西州立大学表示水文地质学中流体流动的控制物理的传统方法是基于以下前提：(a)流体流动可以与固体基质中的变形分开处理；(b)流动条件的变化是渐进的（即允许简化关于动量变化的假设是有效的）。振荡流在某些“中间”频率范围内可能会违反这些前提，无论它们是为了监测或现场特征而故意在井中产生的，还是由自然或人为来源意外产生的。这些违反为理解地下多孔介质在岩心和野外尺度（即水文应用中感兴趣的尺度）下的振荡流体流动提出了重要问题：(a)必须修改达西定律吗？(b)控制水力参数，如渗透率和弹性储存是否随振荡频率而变化，而不是保持不变？本研究是对中频振荡流动的全面研究，包括：在孔隙尺度上对流动进行仔细的数学研究，并将其提升到核心尺度以推广达西定律；在实验室沙盒中进行实验，以测试/验证理论发展，并检查包括非混相流体渗透在内的异质情况；在一个高度表征的研究井田，通过控制振荡流实验，将规模提升到水文尺度，以测试/验证理论发展和模型。预期结果包括对振荡流动力学的严格理论处理，从而在实验室和现场尺度上预测和建模振荡信号传播特征和频率相关的含水层参数行为，适用于一系列多孔介质材料。这个项目对整个社会以及科学界和工程界都有广泛的影响，因为它涉及地下的基本水文研究，而地下是大多数可用淡水的储存地。在美国，地下水是超过50%的美国人的主要水源，大约95%的美国人生活在农村地区。在世界上，许多最重要的含水层正在逐渐枯竭或受到污染。这项研究将为这一重要资源的恢复和管理提供更好的方法。特别是，振荡流可能成为表征地下体积的重要工具，以确定含水层参数的三维非均质性，并监测水质或含水层状态的变化，而无需去除水（可能受到污染和危险）。振荡流在增强混合方面也有潜在的应用，它可以提高反应速率并产生更有效的场地修复技术。

Collaborative research: Fundamental Research on Oscillatory Flow in HydrogeologyPeter Kitanidis, Stanford UniversityMichael Cardiff, University of WisconsinWarren Barrash, Boise State UniversityThe conventional approach to representing the governing physics of fluid flow in hydrogeology is based on the premises that (a) fluid flow can be treated separately from deformation in the solid matrix and (b) changes in flow conditions are gradual (i.e., allowing simplifying assumptions about momentum changes to be valid). Oscillatory flows may violate these premises in certain "intermediate" frequency ranges, regardless of whether they are created deliberately at a well for purposes of monitoring or site characterization, or are created accidentally from a natural or man-made source. These violations raise important questions for understanding oscillatory fluid flow in subsurface porous media at core and field scales (i.e., scales of interest in hydrologic applications): (a) must Darcy's law be modified? and (b) do controlling hydraulic parameters such as permeability and elastic storage change with oscillation frequency rather than remain constant? This research is a comprehensive study of oscillatory flows at intermediate frequencies involving: a careful mathematical study of flow at the pore scale and upscaling to the core scale to generalize Darcy's law; experiments in a laboratory sandbox to test/validate the theoretical developments and examine heterogeneous cases including infiltration of an immiscible fluid; and upscaling to hydrologic scale with controlled oscillatory flow experiments in the field at a highly characterized research wellfield to test/validate theoretical developments and models. Expected results include a rigorous theoretical treatment of oscillatory flow mechanics leading to predictions and modeling of oscillatory signal propagation characteristics and frequency dependent aquifer parameter behavior at laboratory and field scale for a range of porous media materials. This project has broad impacts for society overall and for the scientific and engineering communities because it deals with basic hydrologic research in the subsurface, where most of the available freshwater is stored. In the United States, groundwater is the primary source of water for over 50 percent of Americans, and roughly 95 percent for those in rural areas. In the world, many of the most important aquifers are being gradually depleted or contaminated. This research will lead to better methods for the restoration and management of this important resource. In particular, oscillatory flows may become important tools for characterization of subsurface volumes to determine the 3D heterogeneity of aquifer parameters and to monitor for changes in water quality or aquifer status without having to remove water (that may be contaminated and hazardous). Oscillatory flows also have potential applications in enhancing mixing, which can enhance reaction rates and result in more efficient site remediation technologies.