Colloid dynamics in porous media induced by fluid flow and solute transport

这项建议的目的是确定胶体颗粒在多孔介质中的运动如何受到流体流动和流体中溶解溶质的存在的影响。溶质浓度的变化可以影响胶体颗粒通过随机的孔隙或通道网络的运动。该项目将利用微流体实验来探索溶质浓度梯度影响胶体颗粒运动的机制，这可能导致颗粒在多孔基质中积累并堵塞某些通道。这项研究的结果将直接关系到重要的工业和自然发生的过程，如化学提高采油(EOR)。化学三次采油工艺，包括表面活性剂驱、聚合物驱和低矿化度水驱，已显著提高了美国油层的产量。提高采收率通常涉及胶体悬浮液通过含有各种溶质化学浓度变化的多孔地下表面的流动。多孔介质中不均匀的化学环境可能会导致胶体颗粒发生强烈的定向运动，从而导致意外的胶体动力学，并可能影响三次采油的性能和效率。本项目的两个目标是定量表征流动接头中的胶体扩散扩散和研究油滴在多孔介质中的扩散渗透和马兰戈尼推进作用。该项目将包括不同参数下溶质梯度诱导胶体运动的实验研究。微流控工具将被用来精确控制实验条件，荧光显微镜和3D高速成像将被用来测量胶体运动。这些实验将模拟化学提高采收率过程的真实条件，从而阐明溶质运移对随机多孔介质中硬胶体和软胶体运动的影响。数值模拟和降阶分析模型将补充实验观察，并对溶质梯度诱导的胶体动力学提供进一步的见解。微流体学实验和数值模拟的结合为交通现象的跨学科研究和教育提供了一个引人注目的机会。研究活动将被纳入针对工程学学生的教育努力，以及旨在鼓励代表不足的少数族裔学生，特别是夏威夷原住民和太平洋岛民，学习微流体和运输现象的外展努力。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。

The goal of this proposal is to identify how the motion of colloidal particles in a porous medium is affected by fluid flow and the presence of dissolved solutes in the fluid. Variations in solute concentrations can influence the motion of the colloidal particles through a random network of pores or channels. This project will use microfluidic experiments to explore the mechanisms by which solute concentration gradients affect the motion of colloidal particles, which can lead to accumulation of the particles and blockage of certain channels within the porous matrix. The results of this research will be directly relevant to important industrial and naturally-occurring processes such as chemical enhanced oil recovery (EOR). Chemical EOR processes, including surfactant flooding, polymer flooding, and low-salinity water flooding, have significantly enhanced production from oil reservoirs in the US. EOR often involves flow of colloidal suspensions through a porous subsurface containing variations in chemical concentrations of various solutes. The non-uniform chemical environment in the porous medium may cause the colloidal particles to undergo a strong directed motion, which may lead to unexpected colloid dynamics and may influence EOR performance and efficiency.The two aims of the project are to characterize quantitatively colloid diffusiophoresis in flow junctions and to investigate diffusiophoresis and Marangoni propulsion of oil drops in porous media for chemical EOR processes. The project will include experimental studies of the solute-gradient-induced colloid motion for various parameters. Microfluidic tools will be used to precisely control experimental conditions, and fluorescence microscopy combined with 3D high-speed imaging will be used to measure colloid motion. The experiments will mimic realistic conditions for chemical EOR processes so that results elucidate effects of solute transport on the motion of hard and soft colloids in random porous media. Numerical simulations and reduced-order analytical models will complement the experimental observations and provide further insights into the solute-gradient-induced colloid dynamics. The combination of microfluidics experiments and numerical modeling provides a compelling opportunity for interdisciplinary research and education in transport phenomena. The research activities will be integrated into an educational effort directed toward engineering students as well as an outreach effort aimed at encouraging under-represented minority students, especially native Hawaiians and Pacific Islanders, to study microfluidics and transport phenomena.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.