The Dynamics of Curved Fluid Films Between Complex Interfaces

薄膜的动力学对于液滴的聚结、泡沫稳定性、所有类型的润滑剂的作用以及各种“干燥”现象（包括油漆和涂料的流平）至关重要。在我们的身体中，薄膜在许多过程中发挥着关键作用，包括吸入后空气的清洁、通过所谓的“泪膜”在各种条件下看清的能力以及单个红细胞在毛细血管中传输氧气的能力。现在已经知道，并且在过去十年的实验中反复证明，薄膜中非常小的不均匀性（即杂质）会产生与时间相关且混乱的薄膜厚度模式，这些动态甚至可能导致一种新的“湍流”，而对这些复杂模式的形成的物理理解很少，而这些复杂模式一旦出现，就会完全控制薄膜的寿命和演变，因此，例如，它们决定了泡沫是否稳定或不稳定，或者润滑剂是否失效或仍然有用。整合理论、数值模拟和实验，以加深对这些复杂动力学及其可能发生条件的物理理解。研究期间学到的知识将在斯坦福大学的两个班级中传播，三名高中教师将通过暑期实习参与研究，而斯坦福大学 STAR（通过艺术进行科学教学）计划将突出这些薄膜动力学的自然美，并以视觉方式开发吸引人的故事，以吸引包括高中生和社区大学生在内的广大受众。为了实现对这些薄膜混沌动力学的理解，该研究将采用。通过润滑或“薄膜”理论进行直接数值模拟（DNS）——因此，即使采用“薄膜”假设，该研究也将通过与先前完成的实验相关的参数体系来阐明形成这些模式的条件和机制是什么。该模拟将与其他实验相结合，以直接测试新的物理理解是否已成功建模。从根本上改变了复杂界面之间薄膜动力学的研究。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The dynamics of thin films are critical to the coalescence of drops, foam stability, the action of lubricants of all types, as well as, “drying’’ phenomena of all kinds, including the levelling of paints and coatings. In our bodies, thin fluid films play a key role in a wide array of processes including the cleaning of the air after inhalation, the ability to see clearly under all kinds of conditions through the so-called “tear film”, and the ability of single red blood cells to transfer oxygen in capillaries. It is now known and has been demonstrated repeatedly in experiments over the last decade that very small inhomogeneities in the films (i.e. impurities), generate film thickness patterns that can be time dependent and chaotic. These dynamics can even lead to a new kind of “turbulence”. There is very little physical understanding of the formation of these complex patterns, which, once they appear, completely control the lifetime and evolution of the thin films. So, for example, they determine whether a foam is stable or unstable or whether a lubricant fails or remains useful. The research integrates theory, numerical simulations, and experiments to develop a physical understanding of these complex dynamics and the conditions in which they may occur. The knowledge learned during the research will be disseminated in two classes at Stanford, three high school teachers will be involved in the research with summer internships, and the Stanford STAR – Scientific Teaching Through Art – program will highlight the natural beauty of the dynamics of these films and visually develop appealing stories to reach a broad audience including high school and community college students.To accomplish the understanding of these thin film chaotic dynamics the research will employ direct numerical simulation (DNS) via a lubrication or “thin film” theory– thus even with the “thin film” assumption a large numerical solution is required. The research will elucidate via numerical simulation over parameter regimes associated with previously accomplished experiments, what are the conditions and mechanisms for the formation of these patterns. The simulations will be coupled with additional experiments to directly test whether a new physical understanding has been successfully modelled. The research goal is to delineate the parameter regimes where prior simplifying assumptions regarding space and time development are not valid, thus fundamentally changing the study of thin film dynamics between complex interfaces.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.