Experiments on fluids and grains

流体和颗粒实验

• 批准号: 1404841
• 负责人: Sidney Nagel
• 金额: $ 47.4万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1404841&HistoricalAwards=false
• 关键词: Experiments; fluids; grains

Non-Technical AbstractThis project focuses on a set of far-from-equilibrium phenomena in fluids that seemingly defy our intuition. There are six specific goals: (i) to understand the mechanism of how a liquid drop splashes when it hits a dry solid substrate. It was found that the removal of the ambient air can completely suppress a drop's ability to splash; (ii) to study how the viscous-fingering instability, which occurs as a less viscous fluid displaces a more viscous one in a thin gap between two flat plates, changes its fundamental nature when the stabilizing force, the surface tension, is removed. It was found that, instead of becoming more unstable, it can stop fingering completely; (iii) to understand how fluid drops coalesce when they merge inside an outer fluid. It was found that the viscosity of the outer fluid often plays an insignificant role in the dynamics; (iv) to measure the dynamics of a Leidenfrost drop. Such drops float on a layer of their own vapor; (v) to study how energy is dissipated in the collision between two clusters of particles. The energy is rapidly lost as jamming fronts sweep across the clusters; (vi) to investigate a new form of memory that is stored in the transient behavior of a fluid before it reaches its final steady state. Such memories initially remember all inputs but then lose the ability to remember them even as they are continually applied.There are three distinct aspects of broader impacts that will be addressed: (i) The phenomena addressed have important implications for technological processes; (ii) Bringing young scientists, from high-school students to postdocs, into research will remain a high priority; (iii) Bringing the fascination with cutting-edge science to the general public, including working with museums, will continue to be pursued.Technical AbstractThis project seeks to investigate fluids that are in states far-from-equilibrium. The first topic is to understand the mechanism whereby removing the ambient air can completely suppress a drop's ability to splash. A second topic is to study how the viscous-fingering instability in the Hele-Shaw geometry becomes more stable when the stabilizing force, the surface tension, is removed. A third project will be to understand how fluid drops coalesce when they merge inside an outer fluid. In a fourth experiment, the dynamics of a Leidenfrost drop will be investigated. A fifth experiment studies how energy is dissipated in the collision between two clusters of particles. Finally, a new form of memory that can be stored in the transient behavior of a fluid before it reaches its final steady state will be studied.There are three distinct aspects of broader impacts that will be addressed: (i) Applications: the phenomena addressed have important implications for technological processes; (ii) Education and Training: bringing young scientists, from high-school students to postdocs, into research will remain a high priority; (iii) Outreach: bringing the fascination with cutting-edge science to the general public, including working with museums, will continue to be pursued.

非技术摘要该项目重点研究流体中的一系列远离平衡的现象，这些现象似乎违背了我们的直觉。 有六个具体目标：（i）了解液滴撞击干燥固体基质时如何飞溅的机制。 研究发现，除去周围空气可以完全抑制水滴飞溅的能力； (ii) 研究当稳定力（表面张力）消除时，粘性指状不稳定性（当粘性较小的流体取代两个平板之间的薄间隙中的粘性较大的流体时发生的现象）如何改变其基本性质。 结果发现，它不但不会变得更加不稳定，反而可以完全停止指法； (iii) 了解流体滴在外部流体内合并时如何合并。 人们发现，外部流体的粘度通常在动力学中起着微不足道的作用； (iv) 测量莱顿弗罗斯特水滴的动态。 这些水滴漂浮在其自身的蒸汽层上； (v) 研究能量在两个粒子簇之间的碰撞中如何消散。 当干扰前沿扫过星团时，能量迅速流失； (vi) 研究一种新形式的记忆，该记忆存储在流体达到最终稳态之前的瞬态行为中。 这种记忆最初会记住所有输入，但随后即使不断应用它们，也会失去记住它们的能力。将解决更广泛影响的三个不同方面：（i）所解决的现象对技术过程具有重要影响； (ii) 让年轻科学家（从高中生到博士后）参与研究仍将是一个高度优先事项； (iii) 将继续追求将尖端科学的魅力带给公众，包括与博物馆合作。技术摘要该项目旨在研究远离平衡态的流体。第一个主题是了解去除周围空气可以完全抑制水滴飞溅能力的机制。 第二个主题是研究当稳定力（表面张力）被消除时，Hele-Shaw 几何中的粘性指法不稳定性如何变得更加稳定。 第三个项目将是了解当流体滴合并到外部流体内时它们如何合并。 在第四个实验中，将研究莱顿弗罗斯特水滴的动力学。 第五个实验研究两个粒子簇之间的碰撞中能量如何消散。 最后，将研究一种新形式的记忆，可以在流体达到最终稳定状态之前将其存储在流体的瞬态行为中。将解决更广泛影响的三个不同方面：（i）应用：所解决的现象对技术流程有重要影响； (ii) 教育和培训：将年轻科学家（从高中生到博士后）带入研究仍然是一个高度优先事项； (iii) 推广：将继续致力于将尖端​​科学的魅力带给公众，包括与博物馆合作。