CBET-EPSRC: Droplet Impact on Fluid Interfaces: 3D Effects Across Scales

在过去的几十年里，人们对跌落撞击问题的解释一直保持着广泛的兴趣。在目前的工作中，我们提出了一个综合的实验，数值和分析研究液滴对流体界面的影响，重点是三维效应。可以说，由于流体流动的高度多尺度性质和强烈的非线性界面变形，精确研究3D影响所需的算法和相关计算能力在最近几年才刚刚开始成熟。同样，可视化和流量测量方面的最新进展现在使这种实验室研究成为可能。我们雄心勃勃的项目汇集了流体动力学领域的不同年轻领导者，以解决这一令人兴奋和紧迫的研究主题，并开发新的变革性框架，利用尖端工具和方法研究这一具有挑战性的问题。液滴-液体撞击是一系列工业应用的基础，如喷雾冷却、燃料喷射、农业应用(如农药喷雾和雨滴影响)、传染病传播、制造应用(如喷墨打印和基于液滴的3D打印)以及环境应用(如溢油补救)。以前关于液滴-液体和液滴-固体碰撞的大量工作主要集中在轴对称、正常碰撞上，这是因为实验表征和可视化相对简单，并且减少了计算需求。在实践中，非轴对称液滴-界面撞击要常见得多，因此扩大目前的理解，包括显式的三维效应，对于解锁和推进应用具有关键和及时的重要性。每项组成研究的目标都将侧重于描述反弹、合并和飞溅三种影响机制之间的参数阈值。这些努力将伴随着降阶模型的开发(以实验和高保真模拟为指导和基准)，以扩展我们结果的实际适用性。这里提出的高度协作的研究计划将在单一框架下完全跨越低能到高能的影响，并允许开发单一、一致的液滴对同一流体液层的影响的物理图像，其中前所未有地关注三维效应、环境气体的作用和流体层的深度。预计研究成果不仅将包括具体的科学发现，还将包括基准和记录的实验和计算工具和数据集，以加强该领域的广泛全球研究努力。此外，PIS将联合开发与拟议工作相关的新的实验和模拟数据可视化活动，以促进英国和美国的科学、外展目的和获取倡议。几位知名艺术家已同意参加流体可视化活动、公开工作室会议和比赛，这些活动将由PI组织，基于他们在科学可视化方面的集体成功记录。

Over the past several decades there has been persistent and broad interest in the elucidation of drop impact problems. In the present work, we propose an integrated experimental, numerical, and analytical investigation of droplet impact on fluid interfaces with a focus on three-dimensional effects. Arguably, the required algorithms and associated computing power needed to accurately investigate 3D impacts are only just starting to mature in recent years due to the highly multi-scale nature of the fluid flow and strongly non-linear interfacial deformations. Similarly, recent advances in visualization and flow measurement have now made such investigations possible in the lab. Our ambitious project brings together a diverse set of young leaders in fluid dynamics to tackle this exciting and pressing research topic, and develop new transformative frameworks to study this challenging set of problems with cutting-edge tools and methodologies. Droplet-liquid impacts are fundamental to a range of industrial applications such as spray cooling, fuel injection, agricultural applications such as pesticide spray, and rain droplet impact, infectious disease transmission, manufacturing applications such as inkjet printing and droplet-based 3D printing, and environmental applications such as oil spill remediation. The bulk of prior work on droplet-liquid and droplet-solid impact focuses on axisymmetric, normal impacts due to the relative simplicity of experimental characterization and visualization and reduced computational demands. In practice, non-axisymmetric droplet-interface impacts are far more common and thus broadening the current understanding to include explicit three-dimensional effects is of critical and timely importance to unlocking and advancing applications. The objective in each constituent study will be focused on delineating parametric thresholds between the impact regimes of rebound, coalescence, and splashing. These efforts will be accompanied by the development of reduced-order models (guided and benchmarked by experiment and high-fidelity simulation) to extend the practical applicability of our results. The highly collaborative research program proposed herein will fully span low-energy to high-energy impacts under a single framework and allow the development of a single, consistent, physical picture for droplet impacts on liquid layers of the same fluid, with an unprecedented focus on three-dimensional effects, the role of the ambient gas, and the depth of the fluid layer. The research outputs are anticipated not only to include the specific scientific discoveries, but also benchmarked and documented experimental and computational tools and datasets to strengthen the broad global research efforts in the area.Moreover, the PIs will jointly develop new experimental and simulation data visualization activities related to the proposed work for the promotion of science, outreach purposes, and access initiatives in both the UK and USA. Several established artists have agreed to participate in visualisation of fluids events, open studio sessions and competitions, which will be organised by the PIs, building on their collective record of success in scientific visualisation.