Collaborative Research: Discontinuous Shear Thickening and Shear Jamming in Dense Suspensions: Statistical Mechanics and the Microscopic Basis for Extreme Transitions of Properties

合作研究：稠密悬浮液中的不连续剪切增稠和剪切堵塞：统计力学和性能极端转变的微观基础

• 批准号: 1605283
• 负责人: Jeffrey Morris
• 金额: $ 23.68万
• 依托单位: CUNY City College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1605283&HistoricalAwards=false
• 关键词: Collaborative; Research; Discontinuous; Shear; Thickening

CBET - 1605283/1605428PI: Morris, Jeffrey F./Chakraborty, BulbulThis collaborative project comprises computational and theoretical studies of the flow of suspensions consisting of solid particles in liquids. The project focuses on concentrated suspensions, where particles occupy more than half of the mixture volume. These are often called dense suspensions, and they are found in application as cement, concrete, and mineral ore slurries. Dense suspensions can change properties suddenly when flow conditions change. In some cases, as the strength of the flow, or shear rate, increases, the mixture can suddenly exhibit an extremely large increase in flow resistance, a phenomenon known as "discontinuous shear thickening" (DST). The flow can even stop, which is known as "shear jamming." DST can have major negative effects on industrial processes involving the mixtures. While DST has been known for many years, it has not been explained. The goal of this project is to determine why this phenomenon happens, which could provide guidance how to design suspensions and processing operations to diminish negative effects of DST. Results of the research will be used in modules that will enable high school students to visualize how many-particle systems result in large-scale behavior, such as DST in cornstarch suspensions, where small grains of starch cause enormous changes in flow properties.The project will explore recent observations that DST can be explained by particle contacts and friction. The work will explore the structure of networks of forces between the particles and how this structure changes as the flow rate is increased to a level causing abrupt changes in properties. In particular, the team will explore whether the flow property transition has the characteristics of a phase transition through simulations of discrete particles in different flows and applications of theoretical concepts from statistical physics. The role of the liquid will be considered by comparing results with the behavior of dry granular systems in which the force network concept and its relation to jamming have been examined by others. This work will probe the relationship of flow-induced property changes to thermodynamic phase transitions and will establish the similarities and differences between different particulate flows. Because solid-liquid mixtures are commonly used in industry and are found in geophysical settings such as mud flows, the project will significantly expand our ability to understand and ultimately predict the dynamics of these complicated systems in important applications.

CBET - 1605283/1605428PI：Morris、Jeffrey F./Chakraborty、Bulbul 该合作项目包括对液体中由固体颗粒组成的悬浮液流动的计算和理论研究。该项目的重点是浓缩悬浮液，其中颗粒占据混合物体积的一半以上。这些通常被称为致密悬浮液，它们被用作水泥、混凝土和矿石浆料。 当流动条件改变时，稠密悬浮液的性质会突然改变。 在某些情况下，随着流动强度或剪切速率的增加，混合物的流动阻力可能突然大幅增加，这种现象称为“不连续剪切增稠”(DST)。 流动甚至可能停止，这被称为“剪切堵塞”。 DST 可能会对涉及混合物的工业过程产生重大负面影响。 虽然 DST 已为人所知多年，但尚未得到解释。 该项目的目标是确定发生这种现象的原因，这可以为如何设计暂停和处理操作以减少夏令时的负面影响提供指导。 研究结果将用于模块中，使高中生能够直观地看到多少颗粒系统会导致大规模行为，例如玉米淀粉悬浮液中的 DST，其中小颗粒淀粉会导致流动特性发生巨大变化。将探索最近的观察结果，即 DST 可以通过粒子接触和摩擦来解释。 这项工作将探索颗粒之间力网络的结构，以及当流速增加到导致性能突然变化的水平时，这种结构如何变化。 特别是，团队将通过对不同流动中离散粒子的模拟以及统计物理学理论概念的应用，探索流动性质转变是否具有相变的特征。 将通过将结果与干颗粒系统的行为进行比较来考虑液体的作用，其中力网络概念及其与干扰的关系已被其他人研究过。 这项工作将探讨流动引起的性质变化与热力学相变的关系，并将建立不同颗粒流之间的异同。 由于固液混合物在工业中普遍使用，并且存在于泥浆流等地球物理环境中，因此该项目将显着扩展我们理解并最终预测重要应用中这些复杂系统动力学的能力。

项目成果

Shear jamming and fragility in dense suspensions

稠密悬浮液中的剪切干扰和脆性

• DOI: 10.1007/s10035-019-0931-5
• 发表时间: 2019-02-12
• 期刊: Granular Matter
• 影响因子: 2.4
• 作者: Ryohei Seto;Abhinendra Singh;B. Chakraborty;M. Denn;J. Morris
• 通讯作者: J. Morris