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: 1916879
• 负责人: Jeffrey Morris
• 金额: $ 29.74万
• 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: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1916879&HistoricalAwards=false
• 关键词: Collaborative; Research; Discontinuous; Shear; Thickening

Materials formed from particles are often handled in the fluid state, such as cement and concrete. These particle-laden fluids have complex flow properties, and understanding the basis for this behavior is critical to design and control of the particle interactions that are responsible for the properties. The surface interactions are also the controlling factor in the behavior of liquid-saturated soils. In the geotechnical context, controlling the interactions is not feasible, but understanding and predicting behavior is especially important. This project seeks to explain the behavior of flowing materials that exhibit very strong property changes. The focus is on suspensions with a high concentration of solid particles in a liquid. These materials often shear thicken, meaning drastically increase their viscosity, such as in cornstarch suspensions in water. This project will use simulation and theoretical methods to examine how the particle forces and surface shape cause shear thickening. Computer simulation models the forces of interaction between the particles and solves for their motion. From the forces and the particle velocities, the flow properties such as the viscosity can be determined, and these are validated against experiments. A set of theoretical tools is applied to describe the forces in the material and how they are connected in a network, much like the connections in a fishnet. The overall goal of the project is to establish a theoretical framework allowing prediction of the flow properties from a knowledge of the basic forces, thus allowing better design in engineering contexts and prediction in geophysical contexts. The team will work with industrial partners in the cement and concrete sector to use the understanding toward design of additives that modify flow behavior while retaining desired properties in the flowing and solid material. Using discrete-particle simulation and statistical mechanical theory, the goal of this project is to develop a statistical mechanical framework that describes the basis for shear thickening and jamming in highly-concentrated suspensions of solid particles in liquids. The contributions of this work will advance the statistical mechanical framework for nonequilibrium suspensions, allowing better ability to predict behavior at the macroscopic scale from a knowledge of the particle interactions. A simulation tool in its established and validated form will be used to explore the nonequilibrium steady states (NESS) ensemble of shear-thickening suspensions under constraints on stress, shear rate, and volume fraction. The ensemble data from simulation will be explored by several theoretical tools, including network theory to establish a structure-property framework appropriate for dense suspensions that approach the jamming condition. A machine learning approach will be applied to advance methods previously developed by the team for prediction of the probability of the stress state based on the microscopic force interactions. Methods from large deviation theory will be used as a framework for describing the fluctuations of properties in NESS ensemble. The simulation method will also be advanced by systematically considering the role of size distribution and particle surface complexity. In addition to simple shear, oscillatory shearing and more complex flow protocols, in which an orthogonal oscillatory component is superimposed on simple shear, will be developed and the results explored by the noted theoretical tools. The research will engage undergraduate, graduate and post-doctoral researchers. The team will prepare technical society short courses and engage in STEM outreach to expose materials physics to K-12 students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

由颗粒形成的材料通常在流体状态下处理，例如水泥和混凝土。这些充满颗粒的流体具有复杂的流动特性，了解这种行为的基础对于设计和控制导致这些特性的颗粒相互作用至关重要。表面相互作用也是液体饱和土壤行为的控制因素。在岩土工程背景下，控制相互作用是不可行的，但理解和预测行为尤其重要。该项目旨在解释表现出非常强烈的属性变化的流动材料的行为。重点是液体中固体颗粒浓度高的悬浮液。这些材料通常会剪切变稠，这意味着它们的粘度急剧增加，例如玉米淀粉在水中的悬浮液。该项目将使用模拟和理论方法来研究颗粒力和表面形状如何导致剪切增稠。计算机模拟模拟粒子之间的相互作用力并求解它们的运动。根据力和粒子速度，可以确定诸如粘度之类的流动特性，并且这些特性可以通过实验进行验证。应用一组理论工具来描述材料中的力以及它们如何在网络中连接，就像鱼网中的连接一样。该项目的总体目标是建立一个理论框架，允许根据基本力的知识来预测流动特性，从而允许在工程环境中进行更好的设计并在地球物理环境中进行预测。该团队将与水泥和混凝土行业的工业合作伙伴合作，利用对添加剂设计的理解，这些添加剂可以改变流动行为，同时保留流动和固体材料所需的性能。该项目的目标是利用离散粒子模拟和统计力学理论，开发一个统计力学框架，描述液体中固体颗粒高浓度悬浮液中剪切增稠和堵塞的基础。这项工作的贡献将推进非平衡悬浮液的统计力学框架，从而能够更好地根据粒子相互作用的知识来预测宏观尺度的行为。已建立并经过验证的模拟工具将用于探索在应力、剪切速率和体积分数约束下剪切增稠悬浮液的非平衡稳态 (NESS) 系综。来自模拟的集合数据将通过多种理论工具进行探索，包括网络理论，以建立适合接近干扰条件的密集悬浮液的结构-性能框架。机器学习方法将应用于该团队之前开发的先进方法，用于根据微观力相互作用预测应力状态的概率。大偏差理论的方法将用作描述 NESS 系综属性波动的框架。通过系统地考虑尺寸分布和颗粒表面复杂性的作用，模拟方法也将得到改进。除了简单剪切之外，还将开发振荡剪切和更复杂的流动协议，其中正交振荡分量叠加在简单剪切上，并通过著名的理论工具探索结果。该研究将吸引本科生、研究生和博士后研究人员参与。该团队将准备技术学会短期课程，并参与 STEM 推广活动，向 K-12 学生展示材料物理学。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Discontinuous shear thickening in dense suspensions: Mechanisms, force networks, and fluctuations

稠密悬浮液中的不连续剪切增稠：机制、力网络和波动

• DOI: 10.1016/j.sctalk.2022.100031
• 发表时间: 2022
• 期刊: Science Talks
• 作者: Morris, Jeffrey F.

Shear thickening in dense bidisperse suspensions

致密双分散悬浮液中的剪切增稠

• DOI: 10.1122/8.0000495
• 发表时间: 2023
• 期刊: Journal of Rheology
• 影响因子: 3.3
• 作者: Malbranche, Nelya;Chakraborty, Bulbul;Morris, Jeffrey F.
• 通讯作者: Morris, Jeffrey F.

Shear stress dependence of force networks in 3D dense suspensions

• DOI: 10.1039/d1sm00184a
• 发表时间: 2021-07-15
• 期刊: SOFT MATTER
• 影响因子: 3.4
• 作者: Edens, Lance E.;Alvarado, Enrique G.;Clark, Aurora E.
• 通讯作者: Clark, Aurora E.

Toward a fluid mechanics of suspensions

悬架流体力学

• DOI: 10.1103/physrevfluids.5.110519
• 发表时间: 2020
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Morris, Jeffrey F.

K -core analysis of shear-thickening suspensions

剪切增稠悬浮液的 K 核分析

• DOI: 10.1103/physrevfluids.7.024304
• 发表时间: 2022
• 期刊: Physical Review Fluids
• 影响因子: 2.7
• 作者: Sedes, Omer;Makse, Hernan A.;Chakraborty, Bulbul;Morris, Jeffrey F.
• 通讯作者: Morris, Jeffrey F.