A Comprehensive Multi-Scale Study of the Impact of Capillary-Held Water Films on Fluid Motion, Transport and Mass Transfer in the Unsaturated Zone

毛细管水膜对非饱和区流体运动、输运和传质影响的综合多尺度研究

• 批准号: 1446264
• 负责人: Tohren Kibbey
• 金额: $ 36.89万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1446264&HistoricalAwards=false
• 关键词: Comprehensive; Multi; Scale; Study; Impact

A Comprehensive Multi-Scale Study of the Impact of Capillary-Held Water Films on Fluid Motion, Transport and Mass Transfer in the Unsaturated ZoneThe knowledge resulting from the project could ultimately lead to improved models for a wide range of unsaturated phenomena important to practical hydrologic, agricultural, and environmental applications, including prediction of water infiltration into soils and flooding during heavy rainfalls, remediating polluted soils and groundwaters, and movement of fertilizers, pesticides, etc. When water drains out of a porous medium, films of water remain behind on solid grain surfaces. For this reason, water films are ubiquitous in the unsaturated zone under dry conditions, and they play a central role in a wide range of phenomena. Although the magnitude of water film area is substantial, sustained mass transfer at air-water interfaces depends on the extent to which films on solid surfaces are hydraulically connected and mobile enough to be replenished from bulk porewater. Recent information has shown that water films on solid grain surfaces are likely orders of magnitude thicker than previously thought, and that their configuration and thickness are dominated by the roughness of solid grain surfaces. The implication of this finding is that flow and transport in water films on solid grain surfaces are likely far greater than previously thought. However, very little quantitative information is available on how flow and transport occur in grain surface-associated water films. This project is aimed at addressing this critical knowledge gap. The proposed work will combine experimental work spanning a range of cutting-edge techniques with a modeling effort to arrive at a quantitative, predictive understanding of the behavior of capillary-held water films in the unsaturated zone. Experiments and simulations will be conducted at scales ranging from the nanoscale to the grain cluster scale. Stereoscopic SEM will be used to create highly detailed surface roughness maps of real grains and grain clusters, and confocal microscopy techniques will be used to study the impact of external inputs (capillary pressure, evaporation) on dynamic film configuration, flow, and advective transport. Work will be focused around four tightly-coupled tasks designed to test the hypotheses of the work, and then explore the implications of the observed sub-pore-scale film phenomena on REV and field scale behaviors.

毛细水膜对非饱和带流体运动、输运和传质影响的多尺度综合研究该项目产生的知识最终可能导致对实际水文、农业和环境应用重要的广泛非饱和现象的改进模型，包括预测水渗入土壤和暴雨期间的洪水，修复受污染的土壤和地下水，以及肥料、杀虫剂等的移动。当水从多孔介质中排出时，水膜留在固体颗粒表面上。 因此，在干燥条件下，水膜在非饱和区普遍存在，并且在多种现象中发挥着核心作用。 虽然水膜面积的大小是相当大的，在空气-水界面处的持续传质取决于固体表面上的膜的水力连接和移动的足以从大量孔隙水补充的程度。 最近的信息表明，固体颗粒表面上的水膜可能比以前认为的要厚几个数量级，并且它们的配置和厚度由固体颗粒表面的粗糙度决定。 这一发现的含义是，固体颗粒表面上的水膜中的流动和运输可能远远大于以前认为的。 然而，很少有定量的信息是如何流动和运输发生在粮食表面相关的水膜。 该项目旨在弥补这一关键的知识差距。 拟议的工作将结合联合收割机实验工作，跨越一系列的尖端技术与建模工作，以达到定量的，预测性的理解的行为，毛细举行的水膜在非饱和区。实验和模拟将在从纳米尺度到晶粒簇尺度的尺度上进行。立体扫描电镜将被用来创建非常详细的表面粗糙度地图的真实的颗粒和颗粒簇，和共聚焦显微镜技术将被用来研究外部输入（毛细管压力，蒸发）的动态膜配置，流动和平流运输的影响。工作将集中在四个紧密耦合的任务，旨在测试工作的假设，然后探索所观察到的子孔尺度薄膜现象对REV和场尺度行为的影响。