CAREER: Fundamental Controls of Transport Attributes from Porous Media Microstructure

清洁的地下水是许多人的主要饮用水来源，也是宝贵的地球资源。地下水污染的风险往往来自自然、农业或工业活动。为了保护这些饮用水水源的安全，了解污染物预计如何在地下移动和扩散是至关重要的。影响污染物运动的一个重要因素是土壤和岩石中称为孔隙的空隙的可变性。当地下水通过形状和大小不同的错综复杂的孔隙时，就会出现复杂的流动模式，这使得流动预测变得复杂。许多地下水流的数学预测忽略了孔隙中复杂的可变性。这种过于简单化导致了流动预测和观测之间的巨大差异。这个项目的中心科学目标是更好地了解污染物的运动是如何通过可测量的毛孔特征来控制的。该项目的第一步将在统计上确定最相关的孔隙属性，以有效地描述岩石中的流动。第二步将应用这种关系来开发一个新的流动和污染物运动的数学模型。总的来说，这项工作将提供更准确的工具来预测污染物的移动并帮助保护水资源。该项目将通过开发一种基于网络的交互式工具来培训学生和水资源管理人员，该工具旨在允许用户在虚拟环境中了解和操纵地下水流动。解决通过非均匀多孔介质的流动和质量传输对于地下水修复、石油开采和岩土工程等许多技术应用来说是核心。目前这样做的方法是有限的，因为随着精度和区域大小的增加，所需的计算变得昂贵。该项目的中心科学目标是建立一种正式的定量关系，解释局部流体速度和整体流动安排如何受到几何孔隙特征的空间相关变化的控制。这种关联将能够仅从孔隙空间的相关统计描述符来预测非高斯速度分布，这反过来又可以用于预测有效的运移。找到这种难以捉摸的联系将大大提高对地下水流动和污染物在任意区域大小的非均质多孔系统中的传输的预测能力。为了实现这一目标，拟议的工作将首先从统计上确定在不同非均质性的数字扫描岩石样本中，潜在孔隙空间的物理属性如何引起速度变化。这些虚拟数据包含结构、流量和运输的详细信息。接下来，新确定的孔隙结构-流动关系将被整合到异常传输行为的领先建模框架中，并对其进行性能评估。主要的教育目标是加强学生对地下水如何流动以及污染物如何在地下水中扩散的理解。这将通过开发可在翻转课堂环境中使用的非专家(针对高中生、大学生和继续教育学生)的互动网络工具来实现。交互式工具设计允许用户操纵地下水模型，以自动生成的图形形式探索结果，并在自我指导的科学方法应用中找到他们自己问题的答案。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Clean groundwater, a primary source of drinking water for many people, is a valuable Earth resource. Risks of groundwater contamination frequently arise from natural, agricultural, or industrial activities. To preserve the safety of these drinking water sources, it is crucial to understand how contaminants are expected to move and spread underground. An important factor that influences the movement of contaminants is the variability of the void spaces in soil and rocks known as pores. Complex flow patterns arise as groundwater moves through intricate pores of different shapes and sizes, which make predictions of flow complicated. Many mathematical predictions of groundwater flow ignore the complex variability in pores. This oversimplification results in a large discrepancy between flow predictions and observations. The central scientific goal of this project is to better understand how contaminant movement is controlled by measurable features of the pores. The first step of this project will statistically identify the most relevant attributes of pores that effectively describe flow in rock. The second step will apply this relationship to develop a new mathematical model of flow and contaminant movement. Collectively, this work will deliver more accurate tools to predict contaminant movement and to help protect water resources. The project will train students and water managers through the development of an interactive web-based tool designed to allow users to understand and manipulate groundwater flow in a virtual environment.Solving the flow and mass transport through heterogeneous porous media is central to many technological applications spanning groundwater remediation, oil recovery, and geotechnical engineering. The approaches to do so are currently limited, because the required calculations become computationally expensive as accuracy and domain size increase. The central scientific goal of this project is to establish a formal quantitative relationship that explains how local fluid velocities and overall flow arrangement are controlled by spatially correlated variations of geometric pore characteristics. This association would enable predicting non-Gaussian velocity distributions from relevant statistical descriptors of the pore space alone, which in turn can be used to predict effective transport. Finding this elusive link will lead to significant improvements in predictive capabilities for groundwater flow and contaminant transport in heterogeneous porous systems of arbitrary domain size. To achieve this goal, the proposed work will first statistically identify how velocity variations are induced by the physical attributes of the underlying pore space in digitally-scanned rock samples of diverse heterogeneities. These virtual data contain detailed information of the structure, the flow and the transport. Next, the newly-determined pore structure-flow relation will be integrated into the leading modeling framework for anomalous transport behavior and assessed for performance. The main educational goal is to enhance student understanding about how groundwater flows and how contaminants spread in it. This will be done through the development of interactive web tools for non-experts (targeting high-school, college and continued education students) that can be used in flipped-classroom environments. The interactive tool design allows the user to manipulate groundwater models, explore the results as automatically-generated graphics, and discover answers to their own questions in a self-directed application of the scientific method.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.