Jamming in Model Supercooled Liquids and Athermal Systems

模型过冷液体和无热系统中的干扰

• 批准号: 0087349
• 负责人: Andrea Liu
• 金额: $ 24.6万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-11-01 至 2004-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0087349&HistoricalAwards=false
• 关键词: Jamming; Model; Supercooled; Liquids; Athermal

0087349LiuThis grant supports theoretical and computational research on the properties of disordered systems. In particular, research will be done on the concept of jamming. Many systems with no quenched disorder can jam, i.e., develop a yield stress or an immeasurably long stress relaxation time in a disordered state. These systems include supercooled liquids, colloidal suspensions, granular materials, emulsions and foams. It has recently been suggested that the onset of jamming might lead to some degree of universality. This is the concept of jamming. Specifically, it has been suggested that different systems should show similar behavior as they jam, and that each system has a jamming phase diagram.The concept of jamming will be explored using numerical simulations on two very different systems that both exhibit transitions to constrained dynamics. The first is a quiescent thermal system, namely a binary Lennard-Jones mixture. This model has been shown to jam as the temperature is lowered to the glass transition. The second system to be studied is a driven, athermal system that has been shown to jam as the shear stress is lowered to the yield stress or as the density of particles is raised above close-packing.One objective of the proposed research is to exploit the idea of jamming to gain new insight into the glass transition by applying recent ideas from granular materials (namely force chains) to supercooled liquids. We will also test the idea of jamming by calculating the complete jamming phase diagram for a binary Lennard-Jones mixture. Finally, we will test whether shear-induced fluctuations can be described by an enhanced effective temperature in binary Lennard-Jones mixtures. The idea of an effective temperature is already widely used to describe unjammed granular materials and needs to be examined carefully.At a minimum, we will learn much more about the behavior of two intriguing systems (supercooled liquids and sheared athermal packings), even if we discover that their connection is only superficial. If the concept of jamming is correct, however, it will be extremely powerful because ideas derived from one system will be applicable to another. The recognition that different systems can be viewed within a broader framework has revolutionalized a number of fields in the past. It is important to explore the avenue of jamming because it may lead to new and deeper understanding of long unsolved problems such as the glass transition.%%% This grant supports theoretical and computational research on the properties of disordered systems. In particular, research will be done on the concept of jamming. Jamming commonly occurs to most of us in the form of traffic jams. As too many vehicles try to pass through a constrained path, the smooth flow of traffic becomes stopped or jammed. Many physical systems comprised of many particles can also jam, i.e., develop a yield stress or an immeasurably long stress relaxation time in a disordered state. These systems include supercooled liquids, colloidal suspensions, granular materials, emulsions and foams. It has recently been suggested that the onset of jamming might lead to some degree of universality among these diverse systems. This is the concept of jamming. Specifically, it has been suggested that different systems should show similar behavior as they jam, and that each system has a jamming phase diagram. In this research the concept of jamming will be explored using numerical simulations on two very different systems that both exhibit transitions to constrained dynamics. ***

0087349Liuthis赠款支持有关无序系统性质的理论和计算研究。 特别是，将对干扰的概念进行研究。 许多没有淬火疾病的系统可以挤压，即，在无序状态下会产生屈服应力或不可估量的长压力放松时间。 这些系统包括超冷液体，胶体悬浮液，颗粒状材料，乳液和泡沫。 最近有人提出，干扰的开始可能会导致一定程度的普遍性。 这是保障的概念。 具体而言，已经提出，不同的系统应显示出类似的行为，并且每个系统都具有堵塞相图。将使用在两个截然不同的系统上使用数值模拟来探索干扰的概念，这两种系统都表现出对受约束动力学的过渡。 第一个是静态的热系统，即二进制Lennard-Jones混合物。 随着温度降低到玻璃转变，该模型已被堵塞。 第二个要研究的系统是一个驱动的，无障碍的系统，由于剪切应力降低到屈服应力或颗粒的密度升高时，该系统已被果酱，或者将颗粒的密度升高到封闭式包装上方。拟议的研究的一个目标是利用Jamming的想法，从而通过从Grenulularemular材料（NaMaly Firice）（NaMaly Foriquains）（超级icool chare）（Namaly celains）（超级固定材料）来获得新的洞察力。 我们还将通过计算二进制Lennard-Jones混合物的完整干扰相图来测试堵塞的想法。 最后，我们将测试剪切诱导的波动是否可以通过二元Lennard-Jones混合物中的有效温度增强来描述。 有效温度的想法已经被广泛用于描述无固定的颗粒材料，并且需要仔细检查。至少，我们将更多地了解两个有趣的系统（超冷液体和剪切的Athermal包装）的行为，即使我们发现它们的连接仅是浅表性的。 但是，如果干扰的概念是正确的，那么它将非常强大，因为从一个系统中得出的想法将适用于另一个系统。 过去可以在更广泛的框架内查看不同系统的认识，过去彻底改变了许多领域。 重要的是要探索干扰的途径，因为它可能会导致对诸如玻璃过渡等长期未解决问题的新更深入的了解。%%％该赠款支持有关无序系统特性的理论和计算研究。 特别是，将对干扰的概念进行研究。 堵塞通常以交通拥堵的形式发生在我们大多数人身上。 随着太多的车辆试图通过约束路径，流量的平稳流就停止或堵塞了。 许多由许多颗粒组成的物理系统也可以堵塞，即，在无序状态下会产生屈服应力或不可估量的较长的应力松弛时间。 这些系统包括超冷液体，胶体悬浮液，颗粒状材料，乳液和泡沫。 最近有人提出，干扰的开始可能会导致这些多样化系统的某种程度的普遍性。 这是保障的概念。具体而言，已经提出，不同的系统应像堵塞一样显示出相似的行为，并且每个系统都具有堵塞相图。 在这项研究中，将使用在两个非常不同的系统上都表现出向受约束动态的两个非常不同的系统上的数值模拟来探讨干扰的概念。 ***