Flow-Induced Alignment of Dispersed Particles: Closure Model for Particle-Fluid Interactions

流动诱导的分散颗粒排列：颗粒-流体相互作用的闭合模型

• 批准号: 9986878
• 负责人: Charles Petty
• 金额: $ 28.5万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9986878&HistoricalAwards=false
• 关键词: Flow; Induced; Alignment; Dispersed; Particles

AbstractThe objective of this project is to develop a closure model for the orientation of particles in a fluid. Model predictions of low-order statistical properties, characteristic of the microstructure of suspensions, are often based on a moment equation for the particle orientation dyadic (second-order moment). The solution to this equation requires a closure model for the particle orientation tetradic (fourth-order moment) associated with particle/fluid interactions. This theoretical work will address a new closure theory for the orientation tetradic that retains the six-fold symmetry and the six-fold projection properties of the exact orientation tetradic. This fundamental research will focus on finding closure approximations of higher order tensors in terms of lower order tensors. The new representation for particle/fluid interactions will be validated for a class of simple flows (shear and extensional) by comparing second-order moment predictions with the exact behavior of the second-order moment derived from the particle orientation distribution function governed by a convective-diffusive type equation. There has been renewed interest in this field for property determination of materials that exhibit a microstructure. Standard industrial flow simulators now incorporate tensor descriptions of particle orientations, and this research may be useful in making those simulations more accurate and efficient.

本项目的目标是建立一个封闭的模型来描述流体中粒子的取向。 模型预测的低阶统计特性，悬浮液的微观结构的特点，往往是基于一个时刻方程的颗粒取向并矢（二阶矩）。 该方程的求解需要与颗粒/流体相互作用相关的颗粒取向四阶矩（四阶矩）的闭合模型。 这项理论工作将提出一种新的取向四元闭合理论，该理论保留了精确取向四元的六重对称性和六重投影性质。这个基础性的研究将集中在寻找高阶张量在低阶张量方面的闭合近似。 粒子/流体相互作用的新表示将被验证为一类简单的流动（剪切和拉伸）通过比较二阶矩的预测与二阶矩的确切行为从粒子取向分布函数由对流扩散型方程。 在这一领域中，人们对表现出微观结构的材料的性能测定重新产生了兴趣。 标准的工业流动模拟器现在结合了粒子取向的张量描述，这项研究可能有助于使这些模拟更加准确和有效。