EAGER: Viability study for interfacial spectroscopy

当液滴受到外力时，它通常会经历其形状的振荡，其频率取决于液滴的材料特性。在一些令人感兴趣的自然发生和技术过程中，水滴的内部含有夹杂物。这些夹杂物可以是小气泡或固体颗粒，可以影响液滴的特征振荡。这项急切的提议的目的是表明，通过测量液滴振荡的频率，可以确定此类包裹体的大小、数量和位置。该项目将使用理论、数值计算和实验相结合的方法来论证这种被称为“界面光谱学”的想法的可行性。在涉及油墨、油漆和其他悬浮液等材料的各种加工操作中，或在检测多相系统中的杂质和污染物时，该结果可用作质量控制工具。该项目将邀请高中生和本科生参与设计和实施实验，以验证方法的有效性。多相系统的自然脉动，如颗粒液滴，呈现出具有有趣的频率和衰减特征的表面波。最近的研究表明，一些模式的频率稍有偏离，就会形成类似于原子能级精细结构分裂的频带。结果表明，这种频率谱和衰变谱对于多相多组分电畴的每个内部结构都是唯一的。这表明有可能从实验测量的界面波谱数据中找到复杂的不透明液体中的东西。这个急切的项目将确立这种诊断技术的可行性和准确性。该项目将集中在四个具体问题上，考虑到携带颗粒的水滴是复杂系统的代表。首先，模拟将演示界面波的频率和衰减常数如何随液滴中颗粒的大小、数量和位置而变化。其次，设计了一种从光谱信息中提取颗粒物细节的反演算法。然后，将该诊断程序应用于实际实验，以测试该技术的性能和局限性。第四，反演的唯一性定理将被推广，看看是否可以使用这种方法来揭示更复杂的结构。这一奖项反映了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。

When a liquid drop is subjected to an external force, it typically undergoes oscillations in its shape with a frequency that depends on the material properties of the drop. In some naturally occurring and technological processes of interest, drops contain inclusions in their interior. These inclusions, which could be small bubbles or solid particles, can affect the characteristic oscillations of the drop. The goal of this EAGER proposal is to show that by measuring the frequency of drop oscillations, the size, number and locations of such inclusions can be determined. The project will use a combination of theory, numerical computations and experiments to demonstrate the feasibility of this idea, which is called “interfacial spectroscopy.” The results could be useful as a quality control tool in a variety of processing operations involving such materials as inks, paints, and other suspensions or to detect impurities and contaminants in multiphase systems. The project will involve high-school students and undergraduates in the design and implementation of experiments to validate the approach.Natural pulsations of multiphase systems like particle-laden drops exhibit surface waves with intriguing frequency and decay features. Recent studies have shown that slightly deviating frequencies for a few modes form bands akin to fine-structure split in atomic energy levels. It can be shown that such frequency and decay spectra are unique for each internal structure of the multiphase multispecies domains. This suggests the possibility of finding what is inside a complicated opaque liquid from experimentally measured interfacial wave spectra data. This EAGER project will establish the viability and accuracy of this diagnostic technique. The project will concentrate on four specific matters considering particle-laden drops to be the representative of complex systems. First, simulations will demonstrate how frequencies and decay constants of interfacial waves vary with size, number and position of the particles inside a droplet. Secondly, an inversion algorithm will be devised to extract the particulate details from spectral information. Then, the diagnostic procedure will be applied in real experiments to test the capability and the limit of the technology. Fourthly, the uniqueness theorem for inversion will be generalized to see whether more complex structures can be revealed using the approach.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.