RUI: Viscosity Imaging and Chemical Reactions as Tools for Control of Fluid Instabilities

RUI：粘度成像和化学反应作为控制流体不稳定性的工具

• 批准号: 1335739
• 负责人: Patrick Bunton
• 金额: $ 17.96万
• 依托单位: William Jewell College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1335739&HistoricalAwards=false
• 关键词: RUI; Viscosity; Imaging; Chemical; Reactions

1335739BuntonThis investigation uses fluorescent probe imaging of the two-dimensional viscosity field during reactive flow, as well as Schlieren imaging, to map how flow instabilities depend on the relative rates of hydrodynamic flow and chemical reactions. The proposed research includes: (1) development of molecular-probe fluorescence imaging technique for in situ monitoring of viscosity applied to a well-characterized miscible and Newtonian glycerol-water system in Hele-Shaw cells; (2) extension of this technique to measure the spatio-temporal evolution of the viscosity field for a chemically-reactive flow system of step-growth polymerization; and (3) investigation of the relative roles of rate of reaction to hydrodynamic flow rate. Intellectual Merit When a high-mobility fluid displaces a fluid of lower mobility, the instability known as fingering occurs. If the two fluids are of comparable viscosity, then the mobility is dominated by density differences and buoyancy-driven convection occurs. If the source of the mobility difference is viscosity, then viscous fingering can occur in a horizontal Hele-Shaw cell. When fluids of differing viscosities and densities are brought together in a gravity field, then the outcome depends on the relative sizes and signs of the stabilizing and destabilizing effects of density and viscosity. This proposal focuses on viscous fingering(VF) in the absence of a gravity field, i.e., in a horizontal Hele-Shaw cell. Despite the central importance of the viscosity profile to experimental interpretation and theoretical models of VF, the viscosity field has yet to be measured in situ during flow. Hence, the actual viscosity gradient must be assumed or interpolated based on a given model. This work develops a technique addressing this issue using a viscosity-sensitive fluorescent probe. After gaining the viscosity field driving VF, one desires to control the field and the instability. A set of step-growth polymerization reactions will be used as model systems in horizontal Hele-Shaw cells because both rate of reactivity and viscosity of the reaction product can be controlled by varying the concentration of the initiator or catalyst or the functionality of the monomers. Schlieren imaging will be used to produce a phase diagram of resultant instability versus rate of reaction and hydrodynamic flow rate. Fluorescent-probe imaging of the viscosity field will provide quantitative data that will be related to theoretical models of the viscosity profile. Broader Impacts Viscous fingering has been studied extensively in part due to its high impact in oil recovery and in pollution spreading in porous media. A large body of literature exists on experimental studies on one hand and on theoretical investigations that focus on computing the spatio-temporal evolution of viscosity fields. A gap exists however in quantitative comparisons between experiments and theory mainly due to the difficulty of quantitative measurements of the evolution in space and time of the local viscosity. This quantitative in-situ monitoring of 2D viscosity field enabling the tuning of the relative reaction and hydrodynamic time scales will broadly impact the field of hydrodynamic instabilities in porous media and will lead to controlling the instability. Additionally, as an outreach, Physics and Elementary Education students will implement a set of optics and fluids activities for middle school students. These activities will be primarily based on the Optics Discovery Kits prepared by the Optical Society of America but with additional demonstrations and activities drawn from fluid dynamics. Supplies will remain with a middle school science teacher in high-need school (such as an Hispanic urban charter school) to empower this teacher to excite future students.

1335739 Bunton这项研究使用荧光探针成像的二维粘度场在反应流，以及纹影成像，以映射流动不稳定性如何取决于流体动力学流动和化学反应的相对速率。拟议的研究包括：（1）在Hele-Shaw池中，发展了分子探针荧光成像技术，应用于已表征的可混溶的牛顿甘油-水体系的粘度的原位监测，（2）将该技术推广到测量逐步增长聚合的化学反应性流动体系的粘度场的时空演化;（3）反应速率对流体动力学流速的相对作用。当一种高流动性的流体取代一种低流动性的流体时，就会发生被称为指进的不稳定现象。如果这两种流体的粘度相当，那么流动性主要由密度差和浮力驱动的对流发生。如果流度差的来源是粘性，则粘性指进可发生在水平Hele-Shaw单元中。当不同粘度和密度的流体在重力场中聚集在一起时，结果取决于密度和粘度的稳定和不稳定效应的相对大小和迹象。该建议的重点是在没有重力场的情况下的粘性指进（VF），即，在一个水平的海勒-肖牢房里尽管中心的粘度曲线的实验解释和VF的理论模型的重要性，粘度场还没有被测量在流动过程中原位。因此，实际粘度梯度必须基于给定的模型来假设或插值。这项工作开发了一种技术，解决这个问题，使用粘度敏感的荧光探针。在获得驱动VF的粘度场之后，人们希望控制场和不稳定性。一组逐步增长的聚合反应将被用作在水平的Hele-Shaw池中的模型系统，因为反应产物的反应速率和粘度都可以通过改变引发剂或催化剂的浓度或单体的官能度来控制。纹影成像将用于生成合成不稳定性与反应速率和流体动力学流速的相图。粘度场的双折射探针成像将提供与粘度分布的理论模型相关的定量数据。粘性指进由于其在石油开采和污染在多孔介质中传播方面的巨大影响而被广泛研究。大量的文献存在于一方面的实验研究和理论研究，侧重于计算的时空演化的粘度场。然而，在实验和理论之间的定量比较中存在差距，主要是由于难以定量测量局部粘度在空间和时间上的演化。这种定量的2D粘度场的原位监测使得能够调整相对反应和流体动力学时间尺度将广泛地影响多孔介质中的流体动力学不稳定性的领域，并将导致控制不稳定性。此外，作为一个推广，物理和小学教育的学生将实施一套光学和流体活动的中学生。这些活动将主要基于美国光学学会准备的光学探索套件，但也有来自流体动力学的额外演示和活动。用品将留在高需求学校（如西班牙裔城市特许学校）的中学科学教师那里，以使这位教师能够激发未来的学生。