RUI: Granular Materials, Fluid Mixing, and Related Nonlinear Phenomena

这个项目的目的是扩大我们对非线性物理现象的理解，特别是那些涉及颗粒材料和流体的现象，使用小规模的实验室实验，并涉及本科生。对于颗粒材料，将利用敏感力测量和对大量颗粒的快速跟踪来确定宏观应力和微观运动。具体实验包括：(A)旋转剪切和空气流态化颗粒材料的研究，以确定动量和能量是如何传输的；(B)平面层的摩擦动力学研究，例如颗粒特性对静态强度和运动的影响；(C)关于倾斜层中的雪崩和流动的实验。颗粒材料的行为将与传统固体和液体的行为进行比较。其中一些实验在理解地球物理现象方面有应用。第二个重点是对流体混合现象的研究，特别是混沌和湍流混合之间的显著差异。精确的成像方法将允许确定控制混合和运输效率的因素，无论是否有化学反应。该项目涉及本科生和博士后实习生，他们将为本科教学和研究都很重要的职业生涯做好准备。%本项目旨在利用小型实验室实验和本科生参与，扩大我们对非线性物理现象的理解，特别是涉及颗粒材料和流体的物理现象。颗粒材料表现出固体和液体状态之间的转变，这对理解地震和雪崩以及制药等材料的工业加工具有重要影响。在即将进行的实验中，将通过各种方式对颗粒材料进行剪切或激励，并将对内力和颗粒运动进行定量研究。将对最新的理论进行测试，以了解和预测这些材料如何流动，以及它们可以承受的内力。第二个重点是研究流体混合现象，即杂质逐渐分散在流体中。了解混乱流和湍流流中混合的显著差异是一个重要的目标。精确的成像方法将允许确定控制混合和运输效率的因素，无论是否有化学反应。该项目涉及本科生和博士后实习生，他们将为本科教学和研究都很重要的职业生涯做好准备。

This project aims at extending our understanding of nonlinear physical phenomena, especially those involving granular materials and fluids, using small scale laboratory experiments and involving undergraduate students. For granular materials, both macroscopic stress and microscopic motion will be determined utilizing sensitive force measurements and rapid tracking of large numbers of particles. Specific experiments include: (a) A study of rotationally sheared and air-fluidized granular material, to determine how momentum and energy are transported; (b) Studies of frictional dynamics of planar layers, e.g. of the influence of particle properties on static strength and motion; (c) Experiments on avalanching and flows in inclined layers. The behavior of granular materials will be compared with that of conventional solids and liquids. Some of these experiments have applications to understanding geophysical phenomena. A second focus is the study of fluid mixing phenomena, especially the dramatic differences between mixing in chaotic and turbulent flows. Precise imaging methods will allow a determination of the factors controlling efficiency in mixing and transport, with and without chemical reaction. The project involves both undergraduate students and a postdoctoral trainee, who will be well prepared for a career in which both undergraduate teaching and research are important.%%%This project aims at extending our understanding of nonlinear physical phenomena, especially those involving granular materials and fluids, using small scale laboratory experiments and involving undergraduate students. Granular materials exhibit a transition between solid and fluid states that has important consequences for understanding earthquakes and avalanches, and for the industrial processing of materials such as pharmaceuticals. In the experiments to be conducted, the granular material will be sheared or excited in various ways, and both the internal forces and particle motion will be studied quantitatively. Tests of recent theories will be made in order to understand and predict how these materials flow, and the internal forces they can sustain. A second focus is the study of fluid mixing phenomena, where an impurity is gradually dispersed in a fluid. Understanding the dramatic differences between mixing in chaotic and turbulent flows is an important goal. Precise imaging methods will allow a determination of the factors controlling efficiency in mixing and transport, with and without chemical reaction. The project involves both undergraduate students and a postdoctoral trainee, who will be well prepared for a career in which both undergraduate teaching and research are important.