Shearing Rheology and Glassy Behavior in Athermal and Thermalized Models of Granular Materials, Simple Liquids, and Amorphous Solids

技术总结该奖项支持关于颗粒材料、玻璃形成简单液体以及泡沫、乳液和胶体等相关软物质系统中平衡和驱动非平衡临界现象的性质的理论研究和教育。利用广泛的数值模拟，PI将研究干扰相图的新区域，这些区域表征了从流动的类液体状态到刚性但结构无序的状态转变的各种物理系统。这项研究将集中于以下活动：(I)PI将研究非热非晶态固体在干扰上方的流变学，表征当一个人接近屈服应力时的奇异行为，并探索其与动态非均质性的关系。(Ii)PI将研究热玻璃化行为与非热干扰转变之间的关系。低温、低剪切应变率下的剪切驱动稳态将作为一种新的探针来证明是否存在真正的奇异热玻璃化转变。(Iii)PI将探索不同动力学对感兴趣的临界行为的影响，特别是粘性耗散的平均场和非平均场模型之间的差异，以及从惯性动力学到过阻尼动力学的交叉。(4)PI将研究摩擦力对剪切驱动非热干扰的影响。在模拟中，将探索新的剪切阻塞状态的实验观测。PI将检查不同的摩擦模型、滑动接触而不是几何粗糙度对模拟现象的影响。这些研究还将涉及从平衡统计力学到根本非平衡系统和驱动稳态的概念和方法的适用性。本科生将参与研究，获得经验、技能和对现代科学研究和数值模拟方法的洞察力。罗切斯特大学有几个SITE REU项目，这些项目极大地有助于吸引高质量的本科生参与暑期研究项目。其中许多在下一年继续进行高级项目或论文。该项目涉及与瑞典乌梅大学以及杜克大学、耶鲁大学和罗切斯特大学的其他研究小组的国际合作。这些互动将为学生提供直接将理论与实验对峙的机会，并使用最先进的高性能计算平台。非技术性总结该奖项支持颗粒和玻璃材料的理论研究和教育，重点是调查从流动的类液体状态到具有无定形结构的刚性状态的表观转变的本质，这些转变发生在颗粒材料、泡沫、胶体、乳液和冷却为玻璃的液体中。对颗粒状和玻璃状材料的了解不仅具有内在的科学价值，而且对从药品加工到种子和谷物的运输，再到材料制造的各种工业过程都很重要。这项研究将有助于颗粒和玻璃材料的知识库，并可能导致现代工业和技术的许多重要领域的进步和效率提高。利用广泛的数值模拟，PI将探索干扰相图的未知区域，该图绘制了材料从流动的类液体状态到刚性但结构无序状态的转变条件。干扰转变发生在远离平衡态的稳定状态。虽然非平衡统计力学的理论还不是很发达，但一个重要的研究方向是研究平衡统计力学的概念和方法在多大程度上可以应用于非平衡系统和驱动稳态领域。国际和平协会将为这一努力作出贡献。PI将探索堵塞转变和冷却液体变成玻璃的转变之间的关系。由于颗粒系统中的能量标度通常比温度高，所以温度通常不会在干扰转变中起作用。PI将使用一种新的策略和创新的技术来研究足够高温下的干扰转变的性质，并将温度下的干扰转变的特征与玻璃化转变进行比较。对颗粒系统的研究往往忽略了颗粒之间的摩擦，但仍然能够观察到堵塞转变。PI计划研究真实颗粒材料中发生的摩擦力对干扰的影响。PI将通过模拟来研究不同的模型，以阐明在剪切应变作用下发生的新的堵塞状态的实验观察。本科生将参与研究，获得经验、技能，并对现代科学研究和数值模拟方法有深入的了解。罗切斯特大学有几个SITE REU项目，这些项目极大地有助于吸引高质量的本科生参与暑期研究项目。其中许多在下一年继续进行高级项目或论文。该项目涉及与瑞典乌梅大学以及杜克大学、耶鲁大学和罗切斯特大学的其他研究小组的国际合作。这些互动将为学生提供直接将理论与实验对峙的机会，使用最先进的高性能计算平台。

TECHNICAL SUMMARYThis award supports theoretical research and education on the nature of equilibrium and driven nonequilibrium critical phenomena in granular materials, glassy forming simple liquids, and related soft matter systems such as foams, emulsions and colloids. Using extensive numerical simulations, the PI will investigate new regions of the jamming phase diagram that characterize a diverse array of physical systems that undergo transitions from flowing liquid-like states to rigid but structurally disordered states. The research will focus on the following activities: (i) The PI will study the rheology of athermal amorphous solids above jamming, characterizing the singular behavior as one approaches the yield stress, and exploring the relation to dynamic heterogeneity. (ii) The PI will investigate the relationship between thermal glassy behavior and the athermal jamming transition. Shear driven steady states at low temperature and low shear strain rate will be used as a new probe to demonstrate whether a true singular thermal glass transition exists. (iii) The PI will explore the effect of different dynamics on the critical behaviors of interest, in particular the difference between mean-field and non-mean-field models of viscous dissipation, and the crossover from inertial to overdamped dynamics. (iv) The PI will study the effect of frictional forces on shear driven athermal jamming. The experimental observation of novel shear jammed states will be explored in simulations. The PI will examine the effect differing models for friction, sliding contacts as opposed to geometric asperities, have on simulation phenomena. These investigations will also address the applicability of concepts and methods from equilibrium statistical mechanics to fundamentally nonequilibrium systems and driven steady states.Undergraduate students will participate in the research, gaining experience, skill, and insight into modern scientific research and methods of numerical simulation. The University of Rochester has several site REU programs that greatly assist in attracting high quality undergraduate students to work on summer research projects. Many of these continue with senior projects or theses during the following year. This project involves international collaboration with Ume¢ªa University in Sweden, as well as other research groups at Duke, Yale, and Rochester. These interactions will provide students with the opportunity to directly confront theory with experiment, to use state of the art high performance computing platforms.NON-TECHNICAL SUMMARYThis award supports theoretical research and education on granular and glassy materials with an emphasis to investigate the nature of the apparent transitions from a flowing liquid-like state to a rigid state with an amorphous structure that occur in granular materials, foams, colloids, emulsions, and liquids cooled to become a glass. The understanding of granular and glassy materials is not only of intrinsic scientific interest, but is important for a wide variety of industrial processes, from the processing of pharmaceuticals, to transportation of seeds and grains, to materials fabrication. This research will contribute to the knowledge base on granular and glassy materials and may lead to advances and improvements in efficiency in many important areas of modern industry and technology. Using extensive numerical simulations, the PI will explore uncharted regions of the jamming phase diagram, a diagram that charts the conditions under which materials undergo transitions from flowing liquid-like states to rigid but structurally disordered states. The jamming transition occurs far from the steady state of equilibrium. While the theory of nonequilibrium statistical mechanics is not well developed, an important research direction is to investigate the extent to which the concepts and methods of equilibrium statistical mechanics can be applied or adapted to the realm of nonequilibrium systems and driven steady states. The PI will contribute to this effort. The PI will explore the relationship between the jamming transition and the transition where a cooling liquid becomes a glass. Because the energy scales in granular systems are usually very high compared to the temperature, temperature does not normally play a role in the jamming transition. The PI will use a novel strategy and innovative techniques to study the nature of the jamming transition at sufficiently high temperatures and compare the signatures of the jamming transition at temperature to the glass transition. Studies of granular systems often neglect friction between particles, but nonetheless are able to observe the jamming transition. The PI plans to study the effect of frictional forces that occur in real granular materials on jamming. The PI will investigate different models through simulation to illuminate experimental observations of novel jammed states that occur under the application of shear strain. Undergraduate students will participate in the research, gaining experience, skill, and insight into modern scientific research and methods of numerical simulation. The University of Rochester has several site REU programs that greatly assist in attracting high quality undergraduate students to work on summer research projects. Many of these continue with senior projects or theses during the following year. This project involves international collaboration with Ume¢ªa University in Sweden, as well as other research groups at Duke, Yale, and Rochester. These interactions will provide students with the opportunity to directly confront theory with experiment, to use state of the art high performance computing platforms.