Collaborative Research: Visualizing the Aging Process in Granular Matter Using Experiment and Simulation

建议编号：0625890和0625149主要研究人员：洛塞特，沃尔夫冈和奥赫恩，科里·S。关系：马里兰大学公园学院和耶鲁大学建议标题：合作研究：使用实验和模拟可视化颗粒物质中的老化过程这个项目的目标是在实验和模拟中研究堵塞的三维粒子系统如何响应外力缓慢重新排列。老化和记忆影响着什么迫使堵塞的颗粒排列开始流动，以及它将如何流动。对堵塞的颗粒物质如何开始流动的基本了解的改善可能会导致这些系统的加工、运输和存储方面的进步，这些系统包括很大一部分工业原材料、食品和药品。具体的进展可能包括1)防止堆积的颗粒介质即使在长时间储存后的灾难性破坏，2)优化土壤沉降的土木工程程序，以及3)更好地了解用于纳米技术应用的高度粘结的堵塞纳米颗粒。颗粒物质中的老化伴随着显著的蠕变或压实，足以引起颗粒接触网络中的重新排列。虽然存在由于蠕变和单个颗粒接触的强化而导致的老化的微观模型，但这些模型没有考虑到接触网络中的这种变化。这个项目将试图了解重排事件如何导致块状材料性质的变化，以及这是否会成为真实材料老化过程中的主导模式。建议的方法是直接想象三维粒子重排，并比较粒子情感和模拟中观察到的动力学(其中可以引入不同的老化规律)。3D排列将使用两种最先进的技术进行成像，这两种技术提供了关于流体浸泡和干燥颗粒物的信息：对流体浸泡的颗粒物进行激光薄片扫描允许对大量数据进行系统扫描。X射线同步加速器显微断层成像技术可以对干燥的颗粒物质进行成像。来自生物学的一种新方法，荧光共振能量转移(FRET)，将被用来直接确定接触网络的关键特征。布罗德影响关于衰老过程中3D粒子重排的实验数据将在网站上公布，以便与其他进行衰老实验、数值或理论工作的人进行比较。通过这个项目，新的科学家将被训练使用强大的实验技术--共聚焦显微镜、X射线断层扫描、FRET和最先进的模拟技术。在欧洲同步加速器获取同步加速器数据将增加学生的国际体验。还将开发演示材料，以突出颗粒流的复杂和意想不到的特性。这些演示将用于本科生课程、大学开放参观和公开演讲。我们将强烈鼓励本科生参与这项拟议的研究。

Proposal Numbers: 0625890 and 0625149Principal Investigators: Losert, Wolfgang and O'Hern, Corey S.Affiliations: University of Maryland College Park and Yale UniversityProposal Title: Collaborative Research: Visualizing the aging process in granular matter using experiment and simulationIntellectual merit The goal of this project is to investigate in experiment and simulation how a jammed three dimensional system of particles slowly rearranges in response to applied forces. Aging and memory affect under what forcing a jammed arrangement of particles will start to flow, and how it will flow. An improved fundamental understanding of how jammed granular matter starts to flow may lead to advances in the processing, transport, and storage of these systems, which includes a large fraction of industrial raw materials, food, and pharmaceutical products. Specific advances may include 1) prevention of catastrophic failure of heaps of granular media even after prolonged storage, 2) optimized civil engineering procedures for the settling of soil, and 3) a better understanding of highly cohesive jammed nanoparticles for nanotechnology applications.Aging in granular matter is accompanied by notable creep or compaction large enough to cause rearrangements in the particle contact network. While microscopic models of aging due to creep and strengthening of individual particle contacts exist, these models do not account for such changes in the contact network. This project will attempt to understand how rearrangement events can lead to changes in bulk material properties and whether this can be the dominant mode in the aging process in a real material.The proposed approach is to directly image three dimensional particle rearrangements, and to compare particlemotion with dynamics observed in simulation (where different aging laws can be introduced) under the same forcing. 3D arrangements will be imaged using two state-of-the-art techniques which provide information about fluid immersed and dry granular matter: laser sheet scanning of fluid immersed granular matter allows for systematic scans of large data volumes. x-ray synchrotron microtomography permits imaging of dry granular matter. A new approach from biology, fluorescence resonance energy transfer (FRET), will be used to determine key features of the contact network directly.Broader ImpactThe experimental data on 3D particle rearrangements during aging will be made available on a website for comparison to others carrying out experimental, numerical, or theoretical work on aging. Through this project new scientists will be trained to use powerful experimental techniques - confocal microscopy, x-ray tomography, and FRET and state of the art simulations. Synchrotron data taking at the European synchrotron will add to the student international experience. Demonstration materials will also be developed to highlight the complex and unexpected properties of granular flows. These demos will be used in undergraduate courses, university open houses, and public lectures. Undergraduate student involvement in the proposed research will strongly be encouraged.