Bridging the Spatial and Temporal Scales in Dense Granular Systems Description of Dense Granular Shear Flows

弥合稠密粒状系统中的时空尺度 稠密粒状剪切流的描述

• 批准号: 0605857
• 负责人: Lou Kondic
• 金额: --
• 依托单位: New Jersey Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605857&HistoricalAwards=false
• 关键词: Bridging; Spatial; Temporal; Scales; Dense

KondicDMS-0605857 The project centers on analyzing and understanding thenature of information propagation through dense granular systems. The properties of the signals are then used to deduce the basicphysical mechanisms of the force and energy transmission. Thesemechanisms have been the subject of considerable study latelybecause it is crucial to understand whether the forces betweengranular particles propagate in a manner that can be describedunder an elliptic, hyperbolic, or parabolic framework. Thestarting point of this project is development of large scalediscrete element simulations that are used to analyze response ofdense granular systems to space- and time-dependentperturbations. The results of the simulations are then employedto help formulate effective models for bridging the scalesbetween micro (grain scale) and meso (hundreds or thousands ofgrains) descriptions of granular systems. Both static anddynamic granular systems are considered, making it possible toanalyze the interplay between granular dynamics and signalpropagation. This setup also allows for considering someimportant features of dense granular flows, such as the role offorce anisotropy and underlying microstructure. The project iscarried out in close collaboration with experimental workperformed at Duke University. Dense granular systems are one of the most challengingsystems in the field of soft condensed matter, in particularbecause they are subject to jamming, and fall in between solidand liquid states of matter. Analysis of signal propagationthrough these systems allows us to understand how granularity ona micro scale influences macroscale behavior. The novel researchtechniques used here also can be applied to other soft condensedmatter systems that experience jamming, such as emulsions,colloids, gels, and foams. In addition, signal propagationthrough granular systems is of considerable importance in anumber of practical problems including oil recovery,vibrofluidized beds, and some important humanitarian efforts,such as detection of land mines. The project addresses basicissues in statics and dynamics of dense granular systems;understanding of these basic concepts allows for future progressin developing better models needed for numerous applications ofgranular materials.

KondicDMS-0605857 该项目的重点是分析和理解通过密集颗粒系统传播信息的性质。然后使用信号的特性来推断力和能量传输的基本物理机制。 这些机制最近已成为大量研究的主题，因为了解颗粒之间的力是否以可以在椭圆形、双曲线或抛物线框架下描述的方式传播至关重要。 该项目的起点是开发大规模离散元模拟，用于分析密集颗粒系统对空间和时间相关扰动的响应。 然后利用模拟结果来帮助制定有效的模型，以弥合颗粒系统的微观（颗粒级）和中观（数百或数千颗粒）描述之间的尺度。 静态和动态颗粒系统都被考虑在内，使得分析颗粒动力学和信号传播之间的相互作用成为可能。 该设置还允许考虑致密颗粒流的一些重要特征，例如力各向异性的作用和底层微观结构。该项目是与杜克大学进行的实验工作密切合作进行的。 致密颗粒系统是软凝聚态物质领域中最具挑战性的系统之一，特别是因为它们容易受到干扰，并且介于物质的固态和液态之间。 对这些系统中信号传播的分析使我们能够了解微观尺度上的粒度如何影响宏观行为。 这里使用的新颖研究技术也可以应用于其他遭受干扰的软凝聚态物质系统，例如乳液、胶体、凝胶和泡沫。 此外，通过颗粒系统的信号传播在许多实际问题中具有相当重要的意义，包括石油采收、振动流化床以及一些重要的人道主义工作，例如地雷探测。 该项目解决了致密颗粒系统的静力学和动力学的基本问题；了解这些基本概念有助于未来在开发颗粒材料众多应用所需的更好模型方面取得进展。