Experiments on fluids and grains

非技术摘要本项目的重点是一组远离平衡现象的流体，似乎违背了我们的直觉。 有六个具体目标：（i）了解液滴在撞击干燥固体基质时如何飞溅的机制。 结果发现，去除周围的空气可以完全抑制一滴的能力飞溅;（ii）研究如何粘性指状不稳定，这是发生在一个较低的粘性流体取代一个更粘的两个平板之间的薄间隙，改变其基本性质时，稳定的力量，表面张力，被删除。 有人发现，而不是变得更加不稳定，它可以完全停止指法;（iii）了解如何流体滴合并时，他们合并内部的外部流体。 结果发现，外流体的粘度往往起着微不足道的作用，在动态;（四）测量动态的莱顿弗罗斯特下降。 这样的水滴漂浮在它们自己的蒸汽层上;（v）研究能量如何在两个粒子团之间的碰撞中耗散。 的能量是迅速丢失的干扰前扫过集群;（六）调查一种新形式的记忆，存储在流体的瞬态行为之前，它达到其最终的稳定状态。 这种记忆最初能记住所有的输入，但后来即使不断地应用，也会失去记住它们的能力，将讨论更广泛影响的三个不同方面：（一）所讨论的现象对技术进程有重要影响;（二）使青年科学家，从高中生到博士后，参与研究仍将是一个高度优先事项;（三）将青年科学家纳入研究领域;（四）将青年科学家纳入研究领域;（五）将青年科学家纳入研究领域。（iii）将继续努力，包括与博物馆合作，使公众对尖端科学产生兴趣。技术摘要本项目旨在研究处于远离平衡状态的流体。第一个主题是了解去除环境空气可以完全抑制水滴飞溅能力的机制。 第二个主题是研究如何在Hele-Shaw几何中的粘性指进不稳定性变得更加稳定时的稳定力，表面张力，被删除。 第三个项目将是了解流体滴在外部流体中合并时如何合并。 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团碰撞时能量是如何耗散的。 最后，将研究一种新形式的记忆，这种记忆可以储存在流体达到最终稳定状态之前的瞬态行为中，将涉及三个不同方面的更广泛的影响：㈠应用：所涉及的现象对技术过程有重要影响; ㈡教育和培训：使青年科学家，从高中生到博士后，参与研究仍将是一个高度优先事项; ㈢外联：将继续努力使公众对尖端科学产生兴趣，包括与博物馆合作。

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.