CAREER: Engineering Interfacial Flows and Instabilities in Solidifying Liquids

模式在自然界中无处不在。从蜂蜜倒在吐司上形成的规则卷曲到蜘蛛网上露珠的有序排列，例子很多。这些结构起源于流体机械不稳定性，已在纯液体(如水和油)的背景下进行了彻底的研究。然而，在现实世界中，流体动力系统往往更为复杂；例如，乳胶最初是一种粘性液体，但在固化后会转变为橡胶。这个职业项目的目标是加深我们对液体凝固过程中流体流动的基本理解。具体地说，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。这一新获得的理解将被用于开发类似3D打印的新制造途径。虽然该项目可能会产生广泛的经济影响，但该研究也将为高中、本科生和研究生提供教育机会，重点是扩大来自代表性不足群体的学生的参与。特别是，固化阻滞流将被用来给流体力学中的抽象概念提供有形的形式。操纵这些物理物体将丰富学生的体验，并点燃他们对蒸汽的兴趣。这一职业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，以加深我们对凝固液体界面流体力学的理解。由于在长度方向上具有良好的缩放性，毛细效应在亚毫米级物体中占主导地位，并在许多工程和自然过程中起着关键作用。因此，界面效应得到了广泛的研究，尽管主要是在牛顿流体中。特别是，流体动力学、凝固和阻止界面流动时形成的固体的形态之间的相互作用仍然知之甚少。此外，界面不稳定性的研究通常接近阈值，因此我们对这些系统中的非线性图案形成的理解是稀疏的。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以及阐明这些系统中的形状-流动耦合来显著推动工程科学的发展。该项目利用稳定性分析，并将通过在力学和材料科学的交汇处提供丰富的、基本上未被探索的问题类别，帮助复兴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。在该项目中获得的新的基本知识将有助于解决所谓的逆问题：找到导致凝固液体流动形成目标形状的最佳初始条件和相互作用集，这一壮举可能会引发新制造方法的发展。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。

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.