RUI: Granular Friction, Fluid Mixing and Related Nonlinear Phenomena

这是一个更新的项目，它将扩展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，使用小规模的实验室实验，并涉及本科生。将对颗粒层中的剪切摩擦现象进行广泛的研究。精确的剪切力测量将与同时进行的显微成像相结合。这些改进将使粘滑运动的开始、前体和向连续滑动的过渡得到详细的研究。其中一个目标是比较颗粒摩擦和固体摩擦。第二个重点将是流体混合现象的研究，其中被动杂质被流动混合。这些实验将包括研究随机细胞流动中的混沌平流，以及颗粒介质中的运输。最后，关于非线性波的模式形成和动力学的持续实验将探索具有多重空间周期性的六边形超晶格模式等现象。这是一个更新的项目，它将扩展我们对非线性物理现象的理解，这些现象可能导致复杂或不可预测的行为。该项目将特别侧重于颗粒状或颗粒状材料和流体，采用小规模实验室实验。培养本科生的研究能力将是这项工作的一个重要方面。将广泛研究受剪切力作用时颗粒状材料层的运动。颗粒层中的剪切摩擦与地震有潜在的重要联系，尽管这些研究的目的是实现基本的理解。精细的力测量将与光学成像相结合，以了解突然滑动事件的发生，以及在主要事件发生之前发生的局部前兆。第二个研究领域将涉及流体混合现象，其中被动杂质被流体输送或混合，其中可能包含多孔介质，如沙子。这类研究可能与土壤中杂质的迁移有关。＊＊＊

9704301 Gollub This is a renewal project which will extend our understanding of nonlinear physical phenomena, especially those involving granular materials and fluids, using small scale laboratory experiments and involving undergraduate students. An extensive study will be made of the phenomena of shear friction in granular layers. Delicate shear force measurements will be combined with simultaneous microscopic imaging. These improvements will allow the onset of stick- slip motion, precursors, and the transition to continuous slipping to be investigated in detail. One goal is to compare and contrast granular friction with solid-solid friction. A second focus will be the study of fluid mixing phenomena, in which a passive impurity is mixed by a flow. These experiments will include investigations of chaotic advection in random cellular flows, and transport in granular media. Finally, continuing experiments on pattern formation and dynamics of nonlinear waves will explore phenomena such as hexagonal superlattice patterns with multiple spatial periodicities. %%% This a renewal project which will extend our understanding of nonlinear physical phenomena that can give rise to complex or unpredictable behavior. The project will focus especially on granular or particulate materials and fluids, using small scale laboratory experiments. The training of undergraduate students in research will be an important aspect of this work. An extensive study will be made of the motion of layers of granular material when subjected to shear forces. Shear friction in granular layers is potentially important in connection with earthquakes, though these studies are aimed at achieving a basic understanding. Delicate force measurements will be combined with optical imaging to understand the onset of sudden slipping events, and the localized precursors that occur in advance of major events. A second area of study will involve fluid mixing phenomena, in which a passive impurity is transported or mixed by a fluid flow, which may contain a porous medium such as sand. Studies of this type may be relevant to the transport of impurities in soils. ***