Development and Validation of Particle-Phase Stress Constitutive Models for Non-Spherical Particles

[854005]几乎所有的固体处理操作都涉及到非球形的颗粒。然而，迄今为止对颗粒材料进行的大多数基础研究都涉及球形颗粒。因此，目前在基础研究中使用的模型粒子与工业中处理的真实粒子的特征之间存在着显著的脱节。虽然工业从业者充分理解颗粒形状对颗粒流动行为的影响是显著的，但颗粒形状在流动颗粒系统中的作用还不清楚。因此，本提案概述了一系列的DEM模拟和补充实验，这将导致对颗粒形状的各种特定特征对整体颗粒流动行为的影响有一个基本的了解。此外，所提出的工作的结果将产生预测非球形颗粒在广泛过程中的流动和偏析行为的一般趋势的能力。拟议的工作有三个具体目标：评估将非球形颗粒建模为连接/重叠球体的集合的DEM模拟的定量准确性。研究颗粒存储装置中颗粒形状对颗粒偏析的影响——工业中的一个重要问题。本研究的智力价值在于将进行非球形相互作用颗粒的模拟和实验，以及将获得关于颗粒形状对散装固体处理影响的新的基本关系和见解。在解决大多数工业相关问题之前，必须考虑真实的粒子特性，而不是理想的光滑、圆形粒子。虽然一个为期三年的项目不可能处理真实颗粒混合物的所有方面（如粒径分布、内聚力、静电行为等），但在颗粒形状的影响上取得进展是颗粒流动领域的一个非常重要的进步。此外，该项目的成功完成与PI的长期目标非常吻合，即开发可用于颗粒流过程设计、放大和优化的第一原理和预测模型。由于研究结果几乎适用于所有涉及非球形颗粒的工业颗粒流，因此本研究将具有广泛的影响。研究结果将对CFD模拟的本构模型进行改进，这些模型已被工业研究人员广泛采用。研究结果还将提出建议，通过改变颗粒形状和/或颗粒大小（基于等效体积直径），以及基于形状和大小的颗粒组成，来减轻料斗卸料过程中的颗粒分离。最后，拟议的研究将通过学生（一名博士生和少数本科生研究人员）参与研究，以及通过期刊出版物和通过大量学生和工业人员的教育向科学界传播研究成果，产生广泛的影响。

0854005Curtis, Jennifer Virtually all solid handling operations involve particles that are non-spherical in shape. However, most fundamental studies of granular material undertaken to date have involved spherical particles. Hence, there is a current significant disconnect between the model particles which are used in fundamental research studies and the characteristics of real particles dealt with in industry. While industrial practitioners comprehend fully that the influence of particle shape on particle flow behavior is significant, the role of particle shape in flowing granular systems is not understood. Hence, this proposal outlines a series of DEM simulations and complementary experiments which will result in a fundamental understanding of the influence of various specific features of particle shape on bulk particle flow behavior. In addition, results from the proposed work will yield the ability to predict general trends in flow and segregation behavior for non-spherical particles in a wide range of processes. The proposed work has three specific objectives: 1. To evaluate the quantitative accuracy of DEM simulations involving non-spherical particles modeled as collections of linked/overlapping spheres 2. To investigate the effect of particle shape on particle segregation in particle storage devices - a significant problem in industry 3. To develop and validate constitutive models for particle-phase stress of non-spherical particles that can be employed in CFD simulations The intellectual merit of the proposed work lies in the simulations and experiments, involving non-spherical interacting particles, which will be conducted, and the novel fundamental relationships and insights, pertaining to the influence of particle shape on bulk solids handling, which will be obtained. Real particle properties, not idealized smooth, round particles, must be considered before most industrially-relevant problems can be tackled. While a three-year project can not treat all aspects of real particles mixtures (e.g. particle size distribution, cohesion, electrostatic behavior, etc.), making headway on the effect of particle shape is a very significant advance in the field of granular flow. In addition, successful completion of this project fits well with the PI's longer term goal of developing first principles, predictive models that can be used for design, scale-up and optimization of particle flow processes. The proposed research will have broad impact since the research results are applicable to virtually all industrial granular flows which involve non-spherical particles. The research results will lead to improved constitutive models for CFD simulations, which are widely employed by industrial researchers. The results will also yield recommendations on ways to mitigate particle segregation during hopper discharge by altering the particle shape and/or particle size (based on equivalent volume diameter), as well as particle composition based on shape and size. Finally, the proposed research will have broad impact via involvement of students (one PhD student as well as minority undergraduate researchers) in the research, and the dissemination of the research findings to the scientific community, both through journal publications and through the education of large numbers of students and industrial personnel.