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

提案编号：0625890和0625149主要研究者：Losert、Wolfgang和O 'Hern、Corey S.附属机构： 马里兰州大学帕克分校和耶鲁大学建议标题：合作研究：可视化颗粒物质的老化过程中使用实验和模拟智力优点这个项目的目标是在实验和模拟研究如何堵塞的三维系统的粒子缓慢地重新排列，以响应所施加的力量。衰老和记忆影响着一个拥挤的粒子排列在什么样的压力下开始流动，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理解的改进可能会导致这些系统的加工，运输和储存的进步，其中包括大部分工业原材料，食品和药品。具体的进展可能包括：1）即使在长时间储存后，也能防止颗粒介质堆的灾难性失效，2）优化土壤沉降的土木工程程序，3）更好地理解纳米技术应用中的高粘性堵塞纳米颗粒。颗粒物质的老化伴随着显著的蠕变或压实，大到足以引起颗粒接触网络的重排。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，但这些模型不考虑接触网络中的这种变化。这个项目将试图了解如何重排事件可以导致散装材料性能的变化，以及这是否可以在老化过程中的主导模式在一个真实的material.The建议的方法是直接成像三维粒子重排，并比较particlemotion与在模拟中观察到的动力学（其中可以引入不同的老化规律）在相同的forcing。将使用两种最先进的技术对3D排列进行成像，这些技术提供了有关流体浸没和干燥颗粒物质的信息：流体浸没颗粒物质的激光片扫描允许对大数据量进行系统扫描。X射线同步加速器显微断层摄影术允许对干颗粒物质成像。一种新的方法，从生物学，荧光共振能量转移（FRET），将被用来确定的关键功能的接触network.Broader ImpactThe三维粒子重排在老化过程中的实验数据将在一个网站上进行比较，其他进行实验，数值或理论工作的老化。通过这个项目，新的科学家将接受培训，使用强大的实验技术-共聚焦显微镜，X射线断层扫描，FRET和最先进的模拟状态。在欧洲同步加速器的同步加速器数据将增加学生的国际经验。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课程，大学开放日和公开讲座。将强烈鼓励本科生参与拟议的研究。

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.