CAREER: Engineering Interfacial Flows and Instabilities in Solidifying Liquids

图案在自然界中无处不在。例如，从蜂蜜倒在烤面包上时形成的规则线圈到蜘蛛网上有序排列的露珠。这些结构源自流体机械不稳定性，其已经在纯液体（例如水和油）的背景下被彻底研究。然而，在真实的世界中，流体动力学系统通常更为复杂;例如，乳胶开始时是粘性液体，但在固化时转变为橡胶。这个CAREER项目的目标是进一步加深我们对凝固液体中流体流动的基本理解。具体来说，该项目将研究可固化弹性体及其最终形成的固体中的流体不稳定性。这种新获得的理解将被用来开发类似于3D打印的新制造途径。虽然该项目可能产生广泛的经济影响，但该研究还将为高中，本科和研究生提供教育机会，重点是扩大代表性不足群体的学生的参与。特别是，固化阻止流动将被用来给流体力学中的抽象概念以有形的形式。操纵这些物理对象将丰富学生的经验，并点燃他们对蒸汽的兴趣。该CAREER奖将支持使用可固化弹性体进行的实验和理论模型的开发，以进一步了解固化液体的界面流体力学。由于有利的尺度随长度的减小，毛细效应对于亚毫米物体是占主导地位的，并且在许多工程和自然过程中起着关键作用。因此，界面效应已被广泛研究，尽管主要是在牛顿流体中。特别是，流体力学，凝固和形态的固体之间的相互作用时，逮捕界面流仍然知之甚少。此外，界面不稳定性的研究往往接近阈值，使我们的理解在这些系统中的非线性图案的形成是稀疏的。在这个项目中，研究人员将通过研究可固化聚合物中粘性射流和薄膜的物理特性，并通过阐明这些系统中的形状-流动耦合来显着推进工程科学。该项目利用稳定性分析，并将通过提供力学和材料科学交汇处的丰富且基本上未探索的一类问题，帮助恢复这一具有重要基础和教育意义的领域。将开发涉及使用模板的新颖实验，以使这些系统中的非线性模式选择和自组装合理化。在项目中获得的新的基础知识将有助于解决所谓的逆问题：找到引导固化液体流形成目标形状的初始条件和相互作用的最佳集合，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的评估来支持。影响审查标准。

Patterns are ubiquitous in nature. Examples range from the regular coils that form when honey is poured onto toast to the orderly arrangement of dewdrops on a spiderweb. These structures originate from fluid mechanical instabilities, which have been thoroughly studied in the context of pure liquids, e.g. water and oil. In the real world, fluid dynamical systems are however often more complex; for example, latex starts as a viscous liquid but transitions to rubber when cured. The goal of this CAREER project is to further our fundamental understanding of fluid flows in the context of solidifying liquids. Specifically, the project will investigate fluidic instabilities in curable elastomers and the solids they eventually form. This newly gained understanding will be leveraged to develop new fabrication pathways akin to 3D printing. While this project could have a broad economic impact, the research will also provide educational opportunities for high school, undergraduate, and graduate students, with focus on broadening participation of students from underrepresented groups. In particular, arresting flows with curing will be used to give tangible forms to abstract concepts in fluid mechanics. Manipulating these physical objects will enrich the students experience and ignite their interest in STEAM. This CAREER award will support experiments carried out with curable elastomers and development of theoretical models to further our understanding of the interfacial fluid mechanics of solidifying liquids. Due to favorable downscaling with length, capillary effects are dominant for submillimetric objects and play a key role in a number of engineering and natural processes. As such, interfacial effects have been widely researched, albeit primarily in Newtonian fluids. In particular, the interplay between hydrodynamics, solidification and the morphology of the solids formed when arresting interfacial flows remains poorly understood. Additionally, interfacial instabilities are often studied close to threshold, such that our understanding of nonlinear pattern formation in these systems is sparse. In this project, the investigators will significantly advance engineering science by studying the physics of viscous jets and films in curable polymers and by elucidating the shape-flow coupling in these systems. The project capitalizes on stability analysis and will help revive this area of great fundamental and educational importance by providing a rich and largely unexplored class of problems at the confluence of mechanics and material science. Novel experiments involving the use of templates will be developed to rationalize nonlinear pattern selection and self-assembly in these systems. The new fundamental knowledge gained in the project will help solve the so-called inverse problem: finding the optimal set of initial conditions and interactions that lead a flow of solidifying liquid to form a target shape, a feat that could spark the development of new fabrication methodologies.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.