CAREER: Thixotropic Yield Stress Fluids - Splashing, Spreading, Sticking

Pi：Ewoldt，RandyProposal编号：1351342拟议的职业项目专注于了解液滴和流体射流的飞溅，这些流体具有复杂的流变性，即它们的行为不同于水等牛顿流体。PI的目标是设计新的流体材料，当流体撞击固体时具有所需的性能。这项研究的重要应用是灭火和涉及涂层技术的制造。智力优势：虽然屈服应力流体是具有非常有用功能的非牛顿流体，但触变性、随时间变化的屈服应力流体仍然不像聚合物熔体和溶液那样被系统地理解。这项建议的主要目标是通过了解触变屈服应力流体液滴撞击固体时发生的详细现象来覆盖这些空白区域。提出了一项实验研究，将利用高速成像和复杂触变行为的流变学表征，分析液滴和喷流在干燥和涂层表面上的冲击实验，作为屈服应力、流动粘度、触变时间尺度和流动历史的函数。其目的是更深入地了解飞溅现象、扩散动力学和基片上的材料沉积模式，以满足新型流体材料灭火的设计目标，并开发新的制造技术。更广泛的影响：除了复杂流体动力学的基本知识外，了解触变流体的飞溅过程还可以导致对社会产生重大影响的实际应用，例如在涂料制造和设计用作消防和防火添加剂的新材料方面。这一结果还可能对喷墨打印和农业喷洒技术产生潜在影响。该提案的教育方面包括旨在吸引高中及以上学生参与的教育活动。有人建议开发“流变学动物园”，这是一个学习模块的集合，将开发出将人类感知与流体材料的流变性联系起来的学习模块。流变学动物园将面向工程学本科生和研究生、本科生艺术设计专业的学生和高中生。这里的提案将建立动物园并建立外联部分，从PI的家庭校园开始，并努力为其他大学和地理区域开展可持续和可复制的外联工作。这将通过课程作业、本科荣誉学分、高中外展、网络视频和广泛传播的DIY指导来实现。

PI: Ewoldt, RandyProposal Number: 1351342The proposed CAREER project is focused on understanding the splashing of drops and jets of fluids that are rheologically complex, i.e., they behave differently than Newtonian fluids such as water. The goal of the PI is to design new fluid materials with desirable properties when the fluid impacts on a solid. Important applications of this research are fighting fires and manufacturing that involves coating technologies.Intellectual Merit:While yield stress fluids are non-Newtonian fluids with very useful functionalities, thixotropic, time-dependent yield stress fluids are still not systematically understood in the way that polymer melts and solutions are. The main objective of this proposal is to cover some of this white space by understanding the detailed phenomena that occur when droplets of thixotropic yield stress fluids impact on solids. An experimental study is proposed that will analyze droplet and jet impact experiments on dry and coated surfaces as a function of yield stress, flow viscosity, thixotropic timescales, and flow history using high-speed imaging and rheological characterization of complex thixotropic behavior. The goal is to use a deeper understanding of phenomena like splash regimes, spreading dynamics, and the material deposition pattern on the substrate, in order to meet design objectives for new fluid materials to fight fires and to develop novel manufacturing technologies. Broader Impacts:In addition to fundamental knowledge on the dynamics of complex fluids, understanding the process of splashing of thixotropic fluids can lead to practical applications with significant impact on society, for example in the manufacturing of coatings and on designing new materials to be used as additives in firefighting and fire prevention. The results can also have potential impacts to inkjet printing and agricultural spraying technologies.The educational aspect of the proposal includes educational activities that aim to engage students from the high school level and above. It is proposed to develop the "Rheology Zoo", a collection of learning modules that will be developed to connect human perception to rheological properties of fluid materials. The Rheology Zoo will target engineering undergraduates and graduate students, undergraduate Art+Design students, and high school students. The proposal here will establish The Zoo and build up the outreach pieces, starting at the home-campus of the PI, and work toward a sustainable and replicable outreach effort for other universities and geographical regions. This will occur through coursework, undergraduate honors credit, high school outreach, web videos, and do-it-yourself instructions for broad dissemination.