ERI: Evolution of Detached Liquid Sheet Edges from Patterned Boundaries

液体片在其边缘处破裂形成液滴的复杂方式对于理解喷雾特性（例如所产生的液滴的最终尺寸）是重要的。由于喷雾在许多涉及液体的自然和工程场景中遇到，因此它们的研究在基础和应用层面都很重要。该项目的目的是开发一个实验平台，以探索微图案化边界的演变和随后的液体片边缘的分裂的作用。项目结果可用于验证破碎机制的数值和计算研究。该项目是工程研究启动计划的一部分，将在一所主要为本科生服务的高等教育机构进行，并将为现有基于项目的课程的学生团体提供开发实验设备的机会。其他学生参与者将受益于现有的校园计划-其中一个直接与大学努力改善和促进STEM的多样性，公平性和包容性-提供出色的指导和专业发展机会。该项目的目标是通过研究微尺度图案对物理边界的影响来改进实验，以探索液体片边缘的破裂，这是喷雾形成液滴的基础，一旦液体片分离，边缘就会从物理边界产生。以前的实验使用快速加热金属线框来形成液体膜（肥皂膜）的边缘。这个项目提出要回答的关键问题是：（1）不是使用纯金属丝来形成液体片的初始边缘，用于使用快速沸腾来释放边缘的分离实验，可以用微尺度图案来创建边缘或边界，以在该液体膜边缘上诱导已知空间波长的干扰吗？(2)如果这是可能的，调制扰动对边缘演化的影响的性质是什么？(3)那么，是否有可能证明调制的不稳定性增长的测量，以确定，没有歧义，增长最快的波长，以进一步了解的演变和分裂，通过不稳定性，分离的液体片边缘？为了回答这些问题，将使用高速摄影和高空间分辨率进行具有挑战性的实验。通过开发这些实验技术来回答关键问题，该项目将为未来的液膜破裂研究提供有用的途径。该奖项反映了NSF的法定使命，并通过使用基金会的知识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 complex ways in which sheets of liquid break up at their edges to form droplets are important to the understanding of spray characteristics, for example the eventual size of the droplets produced. As sprays are encountered in numerous natural and engineered scenarios involving liquids, their study is important both at a fundamental and applied level. The aim of this project is to develop an experimental platform to explore the role of micropatterned boundaries on the evolution and subsequent breakup of liquid sheet edges. Project results can be used to validate numerical and computational studies of breakup mechanisms. The project, part of the Engineering Research Initiation program, will take place at a primarily undergraduate serving institution of higher education and will give student groups from existing project-based courses the opportunity to develop experimental equipment. Additional student participants will benefit from existing campus programs - one of which is directly tied to university efforts at improving and promoting diversity, equity, and inclusivity in STEM – providing excellent mentoring and professional development opportunities. The goal of this project is to improve experiments to explore the breakup of liquid sheet edges, fundamental to the formation of droplets by sprays, by investigating the influence of micro-scale patterns on the physical boundaries from which the edges are created once liquid sheets are detached. Previous experiments have used rapid heating of metal wire frames to form the edges of liquid films (soap films). The key questions this project proposes to answer are: (1) Instead of using an unadulterated metallic wire to form the initial edge of a liquid sheet for detachment experiments that use rapid boiling to free the edge, can an edge, or boundary, be created with micro-scale patterns to induce disturbances of a known spatial wavelength onto that liquid film edge? (2) If this is possible, what is the nature of the influence of the modulated disturbance on the evolution of the edge? (3) Is it then possible to demonstrate measurements of modulated instability growth to determine, without ambiguity, fastest growing wavelengths to further understand the evolution and breakup, via instability, of the detached liquid sheet edge? To answer these questions, challenging experiments using high-speed photography and at high spatial resolution will be performed. By developing these experimental techniques to answer the key questions, the project will provide useful avenues for future study of liquid sheet breakup.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.