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

这个NSF-EPSRC项目代表了对液滴撞击液体层的综合，全面和跨学科的研究，特别关注应用中经常出现的三维效应。 液滴-液体碰撞对于一系列工业、农业、先进制造、环境和航空航天应用是基础性的。 当液滴撞击液体层时，可能会出现几种不同的结果，包括完全反弹（反弹），合并（沉积）和飞溅。 根据目标领域的利益，这三个不同的结果可以是可取的或不可取的。 扩大我们目前对液滴撞击现象的理解，包括三维效应，对于解锁和推进现实世界的应用至关重要。这项研究计划利用慢动作摄影和尖端的计算机模拟。 牛津大学和沃里克大学的合作者将分别进行高能撞击实验和对所有感兴趣的区域进行直接数值模拟。 来自喷墨印刷和航空航天行业的合作伙伴参与了该项目，确保了知识转移的直接和加速。 液滴撞击现象引人注目的视觉特性也将直接转化为与艺术家和平面设计师合作开展的众多外联活动，目标受众是代表性不足和弱势群体的青年学生。由于实验表征和可视化的相对简单性以及计算需求的减少，大部分关于液滴-液体和液滴-固体撞击的先前工作集中于轴对称的正向撞击。在实践中，非轴对称液滴界面碰撞更为常见。 在高速可视化、流量测量技术、多尺度算法和相关计算能力方面的最新进展将促进所提出的工作计划和目标。本项目的研究包括（一）正常撞击，特别注意间隙气体层的作用，（二）对移动液体层的撞击，和（三）倾斜撞击。 每项研究的重点是划定参数之间的阈值反弹，聚结，飞溅的影响制度，通过综合实验，高保真数值模拟，降阶建模和缩放分析。 预计研究成果不仅包括具体的科学发现，还包括基准和记录的实验和计算工具和数据集，这些工具和数据集将加强该领域广泛的全球研究工作，以及无数相关主题，包括液滴-固体碰撞、颗粒-液体碰撞和液滴-液滴碰撞。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。

This NSF-EPSRC project represents an integrated, comprehensive, and interdisciplinary investigation of droplets impacting onto liquid layers, with particular attention paid to three-dimensional effects that often arise in applications. Droplet-liquid impacts are fundamental to a range of industrial, agricultural, advanced manufacturing, environmental, and aerospace applications. As a droplet impinges on a liquid layer, several distinct outcomes are possible, which include complete rebound (bouncing), merging (deposition), and splashing. Depending on the target area of interest, each of these three distinct outcomes can be either desirable or undesirable. Broadening our current understanding of droplet impact phenomena to include three-dimensional effects is of critical and timely importance to unlocking and advancing real-world applications. This research program makes use of slow-motion photography and cutting-edge computer simulations. Collaborators at the University of Oxford and the University of Warwick will carry out the high-energy impact experiments and direct numerical simulations over all regimes of interest, respectively. Partners from the inkjet printing and aerospace industries are engaged in this project, ensuring a direct and accelerated track for knowledge transfer. The striking visual nature of droplet impact phenomena will also translate directly into the development of numerous outreach activities in collaboration with artists and graphic designers, with a target audience of young students from underrepresented and disadvantaged groups. 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. Recent advances in high-speed visualization, flow measurement techniques, multi-scale algorithms, and associated computing power will facilitate the proposed work plans and objectives. Studies in the present project include (i) normal impacts, with particular attention to the role of the interstitial gas layer, (ii) impacts onto a moving liquid layer, and (iii) oblique impacts. Each study focuses on delineating parametric thresholds between the impact regimes of rebound, coalescence, and splashing through a synthesis of experiments, high-fidelity numerical simulation, and reduced-order modeling and scaling analysis. The research outputs are anticipated not only to include the specific scientific discoveries, but also benchmarked and documented experimental and computational tools and datasets that will strengthen the broad global research efforts in the area, as well as a myriad of related topics including droplet-solid impacts, particle-liquid impacts, and droplet-droplet collisions. Having industrial partners involved in the project will ensure a streamlined pathway for the translation of the scientific advances towards real-world applications.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.