Fluctuations and Flow for Granular Materials

颗粒材料的波动和流动

• 批准号: 9802602
• 负责人: Robert Behringer
• 金额: $ 27万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802602&HistoricalAwards=false
• 关键词: Fluctuations; Flow; Granular; Materials

9802602 Behringer This condensed matter physics project will probe the dynamics of granular materials primarily via experiments but with some theory and computation. Three areas are represented. First is the role of fluctuations in slow granular flows. Experiments will provide precise local and global measures of fluctuations in forces and in kinematic properties of static and slowly sheared ensembles of particles, including both two- and three-dimensional configurations. The goal is to provide a quantitative measure of the length and time scales for these fluctuations, and to guide the development of models that include the effects of fluctuations. Second is the characterization of granular flows in the inertial regime characterized by binary collisions. Experiments will characterize the collective dynamics of colliding particles, and the thermal-like properties of ensembles with a continuous input of energy. Finally, experimental configurations will probe gas flow in fine granular materials, with an eye to quantitatively understanding heaping effects for shaken granular materials. Granular flows of all types are highly important commercially, and this project is should contribute knowledge that is technically relevant, as provide excellent training for students and post-docs in both fundamental and applied areas. %%% This condensed matter physics project is focused on better understanding the flow of granular materials. Such materials are ubiquitous and include food grains, ore, coal, and pharmaceuticals, to name only a few. The processing of these materials is vital to many industries, yet, there is not a solid scientific understanding of how to describe these materials. As a consequence, processes involving granular processing typically operate at 2/3 of design efficiency, and catastrophic failures are frequent. This proje ct identifies three areas of study that will provide deeper scientific understanding with the potential for applications to commercial processes. For slowly flowing systems, we will characterize the nature of fluctuations, which are known to be large, and therefore potentially destructive, but are poorly characterized. For rapidly stirred/shaken systems, experiments will test models based on the similarity of these systems to a gas. Finally, for grains that are small enough, such as typical sand, cracking catalyst, or powder, ambient air flow is important. Experiments will characterize the interplay between grain and surrounding gas. This project will also provide technical career training for one to two graduate students as well as training for post- doctoral researchers and undergraduates. ***

9802602 Behringer这个冷凝物理物理项目将主要通过实验探测颗粒材料的动力学，但具有一些理论和计算。 代表三个区域。 首先是波动在慢速颗粒流中的作用。实验将提供精确的局部和全局量度的力量，并在静态和缓慢剪切的颗粒的静态和缓慢剪切的集合的运动特性（包括二维和三维构型）中提供。目的是为这些波动的长度和时间尺度提供定量度量，并指导模型的发展，包括波动的影响。其次是以二进制碰撞为特征的惯性状态中颗粒流的表征。 实验将表征碰撞颗粒的集体动力学，以及具有连续能量输入的合奏的热性能。最后，实验构型将探测精细颗粒材料中的气流，以定量地了解摇动颗粒材料的堆积效应。 各种类型的颗粒流在商业上都非常重要，该项目应在技术上相关的知识，因为为基本和应用领域的学生和培训提供了出色的培训。 %% %%这个冷凝的物理项目的重点是更好地了解颗粒材料的流动。 此类材料无处不在，包括食品谷物，矿石，煤炭和药品，仅举几例。这些材料的处理对许多行业至关重要，但是，对如何描述这些材料没有牢固的科学了解。结果，涉及颗粒状加工的过程通常在设计效率的2/3处运行，并且经常发生灾难性的失败。该Proje CT确定了三个研究领域，这些领域将提供更深入的科学理解，并有可能在商业过程中应用。对于缓慢流动的系统，我们将表征波动的性质，这些波动性质很大，因此具有破坏性，但特征的特征很差。对于快速搅拌/摇动的系统，实验将根据这些系统与气体的相似性测试模型。 最后，对于足够小的谷物，例如典型的沙子，破裂的催化剂或粉末，环境气流很重要。 实验将表征谷物与周围气体之间的相互作用。 该项目还将为一到两位研究生提供技术职业培训，并为博士后研究人员和本科生提供培训。 ***