Collaborative Proposal: Long-term dynamics of Water-entry

1336038/1335957 Jung/Vlachos 物体通过流体表面的运动引起了对涉及惯性、重力、粘性力、表面张力和疏水性相互作用的物理过程感兴趣的科学家和工程师的注意。 进水现象在工程应用和自然界中普遍存在。 此类工程应用包括船舶运动、海洋结构-波浪相互作用和弹道学。 生物学的例子包括蛇怪在水面上的运动和动物的饮水过程。 尽管人们对入水物理学非常感兴趣，但统一控制入水过程的所有物理力的方法尚未得到很好的发展。这可以归因于这样一个事实：在进入过程中，所涉及的物理参数的相对重要性不断变化。 这些参数是惯性、重力、表面张力、疏水性和跨界面的压力跃变。 PI 建议进行最先进的实验并开发一个全面的数学模型来捕获所有涉及的物理因素。 在界面动力学建模中，PI 将开发溅幕模型来捕获自由表面上方的圆顶闭合形状，研究夹断后空腔波纹的不稳定性，并解释表面张力的影响以及界面上的压力跃变。 在物理实验中，PI 将定量研究各种控制良好的参数的入水动力学，并介绍一种使用数字粒子图像测速 (DPIV) 速度场测量内部气压的方法。 PI 将进行超快同步加速器 X 射线成像实验，以捕获进水过程中接触线前进的动态。 通过克服当前实验和数学方法的局限性，PI 渴望改变我们对进水过程的理解，并为涉及进水的众多工程应用的进步提供支持知识。 以前的研究只关注惯性和重力，它们在撞击的初始阶段占主导地位，但往往忽略了许多其他物理因素，例如粘性或表面张力效应。 因此，缺乏描述这些物理参数中间范围内的基本力学的模型。 如上所述的生物系统通常在这种中间条件范围内运行。 因此，这项工作的重点是了解在物理参数的中间条件下控制水进入的物理过程。 就更广泛的影响而言，这项研究应该提供工程、数学和物理交叉领域的见解。 这项工作应该加深对进水动力学的理解，并促进新型仿生工程系统的开发，例如，最大限度地减少水冲击时结构的负载和可能的灾难性损坏。 该项目将为研究生和本科生提供跨学科教育，通过先进的实验方法与严格的数学建模相结合的培训。 此外，这项工作的成果和成就将通过 PI 教授的研究生和本科生课程转化为课堂，从而促进欣赏、促进和开发跨学科技术的工程师和研究人员的发展。 PI 将利用当前成功的弗吉尼亚理工大学多样性和外展计划，包括招聘计划和保留与 PI 合作的代表性不足的群体。

1336038/1335957 Jung/VlachosThe motion of an object through a fluid surface has drawn the attention of scientists and engineers interested in physical processes involving the interplay of inertia, gravity, viscous forces, surface tension, and hydrophobicity. Water-entry phenomena are ubiquitous in engineering applications and in nature. Such engineering applications include ship motion, ocean structure-wave interaction, and ballistics. Biological examples include the locomotion of the basilisk lizard on the water surface and the drinking processes of animals. Despite the great interest in water-entry physics, an approach unifying all physical forces governing the water-entry process is not well developed. This can be attributed to the fact that during the entry process the relative importance of the physical parameters involved is continuously changing. These parameters are inertia, gravity, surface tension, hydrophobicity, and the pressure jump across the interface. The PIs propose to perform state-of-the-art experiments and develop a comprehensive mathematical model that captures all physical factors involved. In the modeling of interfacial dynamics, the PIs will develop a splash-curtain model to capture the dome-closing shape above the free surface, investigate the instability of cavity ripples after the pinch-off, and account for the effect of surface tension, as well as pressure jump across the interface. In physical experiments, the PIs will quantitatively study the dynamics of water entry with various well-controlled parameters and introduce a method to measure the internal air pressure using digital particle image velocimetry (DPIV) velocity fields. The PIs will perform ultrafast synchrotron x-ray imaging experiments in order to capture the dynamics of the advancing contact line during water entry. By overcoming the limitations of current experimental and mathematical methods, the PIs aspire to transform our understanding of water-entry processes and provide the enabling knowledge for advances across the numerous engineering applications involving water entry. Previous studies have focused only on inertia and gravity, which are dominant in the initial stage of impact, but they often neglect many other physical factors, such as viscous or surface tension effects. As a result, models describing the fundamental mechanics within the intermediate range of these physical parameters are lacking. Biological systems, such as those described above, often operate within this intermediate range of conditions. Hence, this work is focused on understanding the physical processes governing water entry within the intermediate conditions of the physical parameters. In terms of the broader impacts, this research should provide insights at the interface of engineering, math, and physics. This work should provide an improved understanding of water-entry dynamics and enable the development of novel bio-inspired engineering systems that, for example, minimize loads and possible catastrophic damage on structures upon water impact. This project will provide interdisciplinary education for graduate and undergraduate students by training them in advanced experimental methods combined with rigorous mathematical modeling. Moreover, the results and accomplishments of this work will translate into the classroom through graduate and undergraduate courses that the PIs teach, thus contributing to the development of engineers and researchers that appreciate, promote, and develop cross-disciplinary technologies. The PIs will leverage current, successful Virginia Tech diversity and outreach programs, including recruiting initiatives and retention of underrepresented groups with which the PIs collaborate.