CAREER: An integrated study of wave-particle interaction on liquid interfaces

这个职业项目将研究毫米大小的颗粒如何在振动流体的表面上运动和相互作用。了解小颗粒和液体表面之间的相互作用是一个广泛的研究领域，具有许多应用，包括漂浮垃圾的运输和清除以及与海面合并的雨滴产生的气溶胶。文献中的大多数研究都集中在单个粒子撞击液体表面或多个浮动粒子的情况下。然而，当底部的液浴垂直振动时，出现了一个有趣的区域，它受到的关注要少得多。在这种情况下，当小液滴与反弹引起的表面波相互作用时，它们可能会反弹，甚至沿着液体界面“行走”。这个项目的目标是展示这一中间制度所特有的新动态。研究人员将把实验和理论结合起来，研究新的弹跳和行走模式、相互作用的粒子组的行为，以及从弹跳粒子和水下特征之间的相互作用中出现的新的传输效应。该项目将为高中、本科生和研究生提供新的多学科研究经验和教育模块。研究人员将开发一门新课程，将严格的数学训练与直接接触现实研究环境交织在一起。该项目还将制定具体举措，向受训人员灌输强大的沟通技能，包括为学生设立专门的训练营，以培养科学可视化艺术方面的专门知识。将利用交流和可视化努力，通过一系列外展活动促进STEM的多样性。该项目将开发新的实验技术和数学模型，以产生对毛细管尺寸颗粒与振动液体界面之间相互作用的基本理解。2005年，Yves Courder和他的同事发现，一个毫米级的液滴可以自发地沿着振动的液浴表面行走，通过与它撞击液体表面时产生的波的共振相互作用而自我推进。通过与波场的耦合，这些行走的液滴，或称“步行者”，表现出令人惊讶的丰富的动力学，包括复杂的反弹模式、束缚状态和双重波粒行为。该项目将扩展和开发卓越的沃克动力学，用于与涉及液体界面上的颗粒材料的实际环境相关的基础研究。研究人员首先将重点放在扩大当前弹跳和行走动力学的参数范围，以包括不同形状的流体和固体颗粒的新组合。第二个目标将是研究由波浪介导力耦合的大型步行者群体的新的自组装和集体动力学。最终目的将是研究行走的液滴与液浴底部淹没特征之间的相互作用，包括周期性和无序的底部地形。这类问题将导致更好地了解颗粒和液体界面之间的相互作用，并为开发液体界面上颗粒材料的自组装、颗粒分类和运输的新方法提供设计原则。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。

This CAREER project will investigate how millimeter-size particles move and interact on the surface of a vibrating fluid. Understanding the interplay between small particles and liquid surfaces is a broad area of research with many applications, including the transport and removal of floating litter and aerosol generation from rain drops merging with the sea surface. Most of the studies available in the literature focus on situations involving either a single particle impacting on a liquid surface or multiple floating particles. However, an interesting regime, which has received much less attention, emerges when the underlying liquid bath is vibrated vertically. In this case, small droplets may bounce and even “walk” along the liquid interface as they interact with surface waves caused by rebounds. The goal of this project is to demonstrate new dynamics that characterize this intermediate regime. The investigators will combine experiments and theory to study new bouncing and walking modes, behaviors of groups of interacting particles, and new transport effects emerging from the interaction between bouncing particles and submerged features. This project will provide new multidisciplinary research experiences and educational modules for high school, undergraduate, and graduate students. The investigators will develop a new course that interweaves rigorous mathematical training with direct exposure to realistic research settings. This project will also develop specific initiatives to instill strong communication skills in the trainees, including a dedicated bootcamp for students to develop expertise in the art of scientific visualization. The communication and visualization efforts will be leveraged to promote diversity in STEM through a range of outreach events.This project will develop new experimental techniques and mathematical models to generate a fundamental understanding of the interaction between capillary-size particles and a vibrating liquid interface. In 2005, Yves Courder and co-workers discovered that a millimetric liquid drop can spontaneously walk along the surface of a vibrating fluid bath, self-propelled through a resonant interaction with the waves created when it strikes the fluid surface. By virtue of the coupling with their wave fields, these walking droplets, or “walkers”, exhibit surprisingly rich dynamics, including complex bouncing modes, bound states, and dual wave-particle behaviors. This project will extend and exploit the remarkable walker dynamics for fundamental research relevant to practical settings involving granular materials on liquid interfaces. The investigator will first focus on broadening the current parameter regime of bouncing and walking dynamics to include new combinations of fluids and solid particles of different shapes. The second aim will be to investigate new self-assembly and collective dynamics with large ensembles of walkers coupled by wave-mediated forces. The final aim will be to examine the interaction between walking droplets and submerged features at the bottom of the liquid bath, including periodic and disordered bottom topographies. This class of problems will lead to a better understanding of the interplay between particles and liquid interfaces, and offer design principles for the development of new methods of self-assembly, particle sorting, and transport of granular materials on liquid 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.