RUI: Flow and Rheology of Particle-Fluid Suspensions with Variable Hydrophobicity

1067598 PI：乌特颗粒和颗粒流体系统的流变学是当前重要的兴趣。虽然许多研究都集中在颗粒-流体混合物的堵塞和流动上，但对表面化学的影响（如颗粒的相对疏水或亲水性质）的研究却很少。除了表面化学在土壤力学和工业问题中的相关性外，例如对侵蚀，水径流和过滤的影响，疏水性也提供了颗粒有效凝聚力的控制参数。 最近的应用程序的干扰相图片的胶体系统有吸引力的相互作用是相关的例子介导的表面性质的重要性的颗粒-颗粒的相互作用。 本研究在本科院校（RUI）的建议，旨在系统地研究疏水相互作用的效果，在两个良好的特征旋转鼓的几何形状和堵塞行为，通过收缩流。 流变学和动力学研究系统（i）不同的疏水颗粒的分数和（ii）被淹没在不同极性的溶剂，以调整表面化学效应的重要性。这组实验与影响土壤/水相互作用的土壤颗粒的表面化学直接相关。此外，这些样品可以浸没在不同极性的流体中，以控制表面化学效应的相对重要性。 初步数据显示，疏水颗粒从水中分离的强烈趋势和浸没在相对非极性液体（如异丙醇或己烷）中时的响应降低。 将使用与胶体稳定性相关的已知颗粒/溶剂系统，然后将其扩展到不同极性的可混溶流体，这将允许对疏水颗粒之间的有效内聚力进行微调控制。我们将定量测量有效疏水性，并将其与流动特性（如休止角、堵塞概率、分离效应和流变剪切强度）相关联。与该提案的更广泛影响相关的最终目标是在高度跨学科的研究环境中对本科研究生进行科学培训。该项目将直接涉及多达六名本科研究人员在该计划的持续时间的培训，但预计多达十个可能会受到影响，包括在学年期间的学分无偿研究。此外，我们计划聘请一名高中教师为今年夏天2，以继续教育教师的JMU的使命之一。 学生将接触到材料科学和复杂系统的问题，包括流变学，动力学和图像处理。该计划的参与者将有望参加与NSF研究经验的本科生（REU）在化学和材料科学在JMU网站的活动，成为一个？“学者社区”与其他六十多个夏季本科研究人员在化学和材料科学在JMU。总之，该计划有助于广泛影响未来科学家的管道，从高中到研究生水平，学生在多相流的前沿研究中接受培训。

1067598PI: UtterThe rheology of granular and granular-fluid systems is of significant current interest. While many studies focus on the jamming and flow of particle-fluid mixtures, there has been little work on the effects of surface chemistry, such as the relative hydrophobic or hydrophilic properties of the grains. In addition to the relevance of surface chemistry in soil mechanics and industrial problems, such as effects on erosion, water runoff, and filtration, hydrophobicity also provides a control parameter on the effective cohesion of grains. Recent applications of the jamming phase picture to colloidal systems with attractive interactions are related examples of the importance of grain-grain interactions mediated by surface properties. This Research at Undergraduate Institutions (RUI) proposal aims to systematically study the effect of the hydrophobic interactions in both the well-characterized rotating drum geometry and jamming behavior in flow through a constriction. Rheology and dynamics are studied in systems (i) that vary by fraction of hydrophobic grains and (ii) that are submerged in solvents of different polarities to tune the importance of the surface chemistry effects. This set of experiments has direct relevance to surface chemistry of soil particulates that impact soil/water interactions. In addition, these samples can be submerged in fluids of different polarity to control the relative importance of the surface chemistry effects. The preliminary data show both a strong tendency of hydrophobic grains to segregate from water and a decreased response when submerged in a relatively non-polar liquid like isopropanol or hexane. Known particle/solvent systems relevant to work on colloidal stability will be used and then extended to miscible fluids of different polarities which will allow fine-tuned control of the effective cohesion between hydrophobic grains. We will quantitatively measure the effective hydrophobicity and correlate these with flow properties such as angle of repose, jamming probability, segregation effects, and rheological shear strength.A final objective related to the broader impacts of this proposal is the scientific training of undergraduate research students in a highly interdisciplinary research environment. This project will directly involve the training of up to six undergraduate researchers over the duration of the program, but it is expected that up to ten will likely be impacted including unpaid research for credit during the academic year. In addition, we plan to hire a high school teacher for the summer of year 2, in order to continue one of JMU's missions of educating teachers. The students will be exposed to issues in materials science and complex systems, including rheology, dynamics, and image processing. The participants in this program will be expected to participate in activities related to the NSF Research Experiences for Undergraduates (REU) sites in chemistry and materials science at JMU to become part of a ?"community of scholars" with over sixty other summer undergraduate researchers in chemistry and materials science at JMU. In summary, this program helps serve to broadly impact the pipeline of future scientists from the high school through the graduate level with students trained in cutting-edge research in multiphase flows.