CAREER: Tuning liquid jet and splash dynamics by deformable and heterogeneous boundaries

液体流过气体的稳定性与药物输送、制造工艺和热管理有关。稳定性取决于流动流体的性质以及系统中固体的机械和表面性质。 为了更好地了解这些系统中液体流动的稳定性，本项目将研究固体的性质如何影响自由液体射流和水进入飞溅。具体来说，这项研究将介绍（i）软材料，变形响应流体运动，和（ii）空间不均匀的固体润湿性能的空气，液体和固体相满足。射流中最令人感兴趣的特征是相干液柱分裂成液滴的长度。这里，该长度将通过在孔口处采用可变形喷嘴和不均匀的表面化学（即润湿性质）来控制。在研究入水时，固体撞击物飞溅到液体池中，由此产生的分散液体和夹带空气的空腔行为是感兴趣的。这样的飞溅功能将被修改使用固体弹丸与化学不均匀的表面，并通过顺应性固体膜顶部的液体表面。这些科学努力整合了教育活动，通过讲座，课堂流量控制实验，指导科学博览会项目和教师参与研讨会，吸引当地高中学生和教育工作者参与科学过程。动态三相接触线与软固体的耦合物理特性的表征尚处于起步阶段。这项研究工作旨在探索流体流动的多相界面已通过材料的顺应性和表面处理修改。实验和理论将被用来理解包含上述被动流动改性剂的射流稳定性的物理学。对自由流液体射流中的初始扰动及其抑制的新理解将为变形喷嘴的线性射流稳定性理论的适应提供信息。柔性介质的自由液体表面的修改和固体弹丸的非均匀边界的改变将产生新的理论处理在中等韦伯数的车辆进入水中。因此，将重新定义空腔产生和塌陷的条件，并探讨非轴对称空腔产生升力的极限。实验技术包括高速摄像来捕捉流动特征，数字跟踪来阐明运动学，显微镜来成像表面，和X射线光电子能谱来化学表征固体表面在这个study.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The stability of liquids flowing through gas is relevant to drug delivery, fabrication processes, and thermal management. The stability depends on the properties of the flowing fluid and on the mechanical and surface properties of the solid bodies in the system. To better understand the stability of liquid flow in these systems, this project will study how the properties of solid bodies affect both free liquid jets and water entry splashes. Specifically, this research will introduce (i) soft materials that deform in response to fluid motion, and (ii) spatially nonuniform solid wetting properties where the air, liquid, and solid phases meet. The feature of greatest interest in jets is the length at which the coherent liquid column disintegrates into drops. Here, this length will be controlled by employing deformable nozzles and nonuniform surface chemistry (i.e. wetting properties) at the orifice. In studying water entry, a solid impactor splashes into a liquid pool, and the resulting dispersed liquid and air-entraining cavity behavior are of interest. Such splash features will be modified using both solid projectiles with chemically nonuniform surfaces and via compliant solid films atop the liquid surface. These scientific endeavors integrate educational activities that engage local high school students and educators in the scientific process through lectures, classroom flow control experiments, mentored science fair projects, and research engagement workshops for teachers.The characterization of the coupled physics of dynamic three-phase contact lines with soft solids is in its infancy. This research effort seeks to explore fluid flows where the multiphase interface has been modified via material compliance and surface treatments. Experiments and theory will be used to understand the physics of jet stability with the inclusion of the aforementioned passive flow modifiers. A new understanding of initial disturbances and their suppression within free stream liquid jets will inform the adaptation of linear jet stability theory for deformable nozzles. The modification of free liquid surfaces with compliant media and the alteration of solid projectiles with heterogeneous boundaries will produce new theoretical treatments at moderate Weber numbers for vehicles entering water. Thus, conditions for cavity creation and collapse will be redefined, and the limits of lift force production from non-axisymmetric cavities will be explored. Experimental techniques include high-speed videography to capture flow features, digital tracking to elucidate kinematics, microscopy to image surfaces, and X-ray photoelectron spectroscopy to chemically characterize the solid surfaces used in this study.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.