GOALI: Coating of Rotating Discrete Objects

在非平面离散物体上涂覆液体薄膜出现在各种产品的制造中，例如汽车和航空航天部件、医疗植入物、三维打印部件和食品。通常需要涂层来保护表面或使其功能化，甚至是为了创造最终产品本身。它是美国制造业的一个基本要素。这一学术与工业联系(GOALI)研究的机会促进了这一关键领域的国家繁荣，同时发展了对复杂问题的新的科学见解。与平板上的液膜涂层相比，非平板离散物体上的液膜涂层在基本层面上更难理解。对于大多数应用，需要厚度均匀的涂层。然而，由物体旋转、物体曲率、重力、粘度、表面张力和惯性引起的力之间的复杂相互作用可能会导致不稳定性的增长，从而涂覆不均匀。该项目的总体目标是使用理论、实验和工业交互作用的组合来显著促进对旋转离散物体上的液膜流动的基本理解。这项工作旨在建立的一般原则为工业涂层工艺的系统设计和优化提供了坚实的基础，从而使未来能够实现满足关键行业需求的突破。产业延伸和来自代表性不足群体的本科生参与是对研究活动的补充。该项目使用理论、实验和产业互动的组合来显著促进对液体流变学、非圆形截面和末端效应如何影响旋转离散物体上的液膜流动的基本理解。该理论涉及广义牛顿液体和粘弹性液体的有限差分和有限元模拟。模拟结果给出了涂层厚度和稳定性极限作为表征旋转速度、物体形状和流变性的参数的函数的预测。这些预测，连同对基本方程的渐近分析，被用来生成标度定律，这些定律提供了对工业从业者有帮助的快速准确的估计。实验包括使用具有非圆形横截面的三维打印对象和具有与模拟中使用的流变学模型一致的流变性的液体进行流动可视化。薄膜厚度的变化和不稳定性的开始是由可视化推断的，并与理论预测进行了比较。理论、实验和工业互动之间的相互作用最终促进了对物理的理解，并导致了可应用于涉及离散物体涂层的制造过程的一般原则。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。

Coating of liquid films onto non-flat discrete objects arises in the manufacturing of a broad variety of products such as automobile and aerospace components, medical implants, three-dimensional printed parts, and foodstuffs. Coatings are often needed to protect or functionalize surfaces, or even to create the final product itself. It is an essential element in American manufacturing. This Grant Opportunity for Academic Liaison with Industry (GOALI) research promotes national prosperity in this critical area while developing new scientific insights into a complex problem. In contrast to liquid-film coating on flat substrates, liquid-film coating on non-flat discrete objects is considerably more challenging to understand at a fundamental level. For most applications, a coating of uniform thickness is desired. However, the complex interplay between forces arising from object rotation, object curvature, gravity, viscosity, surface tension, and inertia may lead to the growth of instabilities and thus coating non-uniformities. The overall objective of this project is to use a combination of theory, experiment, and industrial interaction to significantly advance fundamental understanding of the flow of liquid films on rotating discrete objects. The general principles that the work aims to establish provides a firm foundation for systematic design and optimization of industrial coating processes, thereby enabling future breakthroughs that address critical industry needs. Industrial outreach and involvement of undergraduate students from underrepresented groups complement the research activities.This project uses a combination of theory, experiment, and industrial interaction to significantly advance fundamental understanding of how liquid rheology, non-circular cross sections, and end-effects influence the flow of liquid films on rotating discrete objects. The theory involves finite-difference and finite-element simulations of generalized Newtonian liquids and viscoelastic liquids. The simulations yield predictions of coating-film thickness and stability limits as function of parameters characterizing rotation velocity, object shape, and, rheological properties. These predictions, along with asymptotic analysis of the underlying equations, are used to generate scaling laws that provide quick and accurate estimates helpful for industrial practitioners. The experiments involve flow visualizations using three-dimensional printed objects having non-circular cross sections and liquids having rheological properties consistent with the rheological models used in the simulations. Film-thickness variations and the onset of instabilities are inferred from the visualizations and compared to the theoretical predictions. The interplay between theory, experiment, and industrial interaction ultimately advances physical understanding and lead to general principles that can be applied in manufacturing processes involving the coating of discrete objects.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.