Collaborative Research: Near-Surface Repulsion and Mixing-Limitations: Upscaling of Colloid Transport in Non-Uniform Media under Unfavorable Conditions

合作研究：近表面排斥和混合限制：不利条件下非均匀介质中胶体输运的升级

• 批准号: 1215726
• 负责人: William Johnson
• 金额: $ 22.03万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1215726&HistoricalAwards=false
• 关键词: Collaborative; Research; Near; Surface; Repulsion

Collaborative Research: Near-Surface Repulsion and Mixing-Limitations: Upscaling of Colloid Transport in Non-Uniform Media under Unfavorable ConditionsWilliam Johnson, University of UtahMarkus Hilpert, Johns Hopkins UniversityTimothy Ginn, University of California-DavisThe profound influence of repulsive colloid-surface interactions on colloid transport under environmental conditions (so-called unfavorable conditions) has rendered quantitative prediction of colloid transport in porous media under these conditions unattainable to date. A major question is whether surfaces can generally be interpreted/categorized in terms of a bulk repulsive surface that includes attractive "heterodomains" of given size and spatial frequency (surface coverage). Specifically, it is unknown whether characterizing surfaces in this way allows prediction of colloid transport in porous media under unfavorable conditions. This discrete heterogeneity model predicts (and experiments indicate) that a fraction of colloids in the fluid surrounding a porous media grain will spend long residence times in the near-surface fluid due to weak attractive interactions, which raises another fundamental question: how do the long residence times of colloids in the near-surface fluid under unfavorable conditions influence transport behavior at the Darcy scale? What scale-up strategies are needed to recognize the influence of long near-surface residence times? This project posits that these long near-surface residence times yield incomplete mixing of colloids across the fluid domain, necessitating memory function/multirate or correlated random walk approaches to upscaling. A recently-developed mechanistic model with heterodomains captures colloid transport and retention behavior at the pore scale under unfavorable conditions. This model will serve as the platform from which to scale up predictions to the Darcy scale under unfavorable conditions. The model results will be compared to experimental results for colloid transport in an impinging jet and in porous media for a range of colloid sizes, solution ionic strengths, and fluid velocities. Anticipated results include producing a mechanistic model that will predict the extent and mode of colloid retention under unfavorable conditions. This project will represent unfavorable surfaces in numerical models of colloid transport in order to provide mechanistic prediction of colloid retention during transport in porous media. The results of this mechanistic model will be used to explore the influence of colloid-surface interaction on strategies to upscale transport prediction from the pore to the Darcy scale. This project will greatly enhance our ability to predict colloid transport under environmental conditions in contexts such as pathogen transport in the environment, and targeted delivery of bacteria with novel metabolic properties.

合作研究：近表面排斥和混合限制：不利条件下非均匀介质中胶体输运的放大William约翰逊，犹他大学Markus Hilpert，约翰霍普金斯大学Timothy Ginn，环境条件下胶体-表面排斥相互作用对胶体输运的深刻影响（所谓的不利条件）已经使得在这些条件下多孔介质中的胶体输运的定量预测至今无法实现。 一个主要的问题是，表面是否可以解释/分类的散装排斥表面，包括有吸引力的“异质结构域”的给定大小和空间频率（表面覆盖）。 具体而言，它是未知的，是否以这种方式表征表面允许预测胶体在多孔介质中的运输在不利的条件下。 这种离散的非均质模型预测（和实验表明），一小部分的胶体在流体周围的多孔介质颗粒将花费长的停留时间在近地表流体由于弱吸引力的相互作用，这提出了另一个基本问题：如何长的停留时间的胶体在近地表流体在不利条件下的影响在达西尺度的传输行为？ 需要什么样的扩大战略来认识长近地表停留时间的影响？ 该项目假定，这些长的近表面停留时间产生不完全混合的胶体在整个流体域，需要记忆功能/多速率或相关的随机游走方法来放大。 最近开发的一个机制模型与heterodomains捕获胶体的运输和保留行为在不利条件下的孔隙尺度。 该模型将作为在不利条件下将预测扩大到达西尺度的平台。 模型的结果将进行比较，在一个冲击射流和多孔介质中的胶体输送的胶体尺寸，溶液离子强度和流体速度的范围内的实验结果。 预期的结果包括产生一个机械模型，将预测在不利条件下的胶体保留的程度和模式。本计画将在胶体输运的数值模式中呈现不利的表面，以提供胶体在多孔介质中输运期间滞留的机械预测。 该机理模型的结果将用于探索胶体-表面相互作用对从孔隙到达西尺度的高级运输预测策略的影响。 该项目将大大提高我们在环境条件下预测胶体运输的能力，例如环境中的病原体运输，以及具有新代谢特性的细菌的靶向递送。