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

0854005 Curtis，Jennifer几乎所有的固体处理操作都涉及非球形颗粒。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的粒子的特性之间存在显著的脱节。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尚未被理解。因此，该提案概述了一系列DEM模拟和补充实验，这将导致对散装颗粒流行为的颗粒形状的各种具体特征的影响的基本理解。此外，从拟议的工作的结果将产生的能力，预测在流动和偏析行为的非球形颗粒在广泛的过程中的一般趋势。建议的工作有三个具体目标：1。为了评估DEM模拟的定量准确性，涉及非球形颗粒建模为链接/重叠球体的集合2。研究颗粒形状对颗粒储存装置中颗粒偏析的影响-这是工业中的一个重要问题3。为了开发和验证本构模型的颗粒相应力的非球形颗粒，可以采用CFD模拟的智力价值的拟议工作在于模拟和实验，涉及非球形相互作用的颗粒，这将进行，和新的基本关系和见解，有关散装固体处理的颗粒形状的影响，这将获得。在解决大多数工业相关问题之前，必须考虑真实的颗粒特性，而不是理想化的光滑、圆形颗粒。虽然三年的项目不能处理真实的颗粒混合物的所有方面（例如颗粒尺寸分布、凝聚力、静电行为等），在颗粒形状效应方面取得的进展是颗粒流领域的一个非常重要的进展。此外，该项目的成功完成非常符合PI的长期目标，即开发可用于颗粒流工艺设计、放大和优化的第一原理和预测模型。由于研究结果适用于几乎所有涉及非球形颗粒的工业颗粒流，因此拟议的研究将具有广泛的影响。研究结果将导致改进的本构模型的CFD模拟，这是广泛采用的工业研究人员。结果还将产生关于通过改变颗粒形状和/或颗粒尺寸（基于等效体积直径）以及基于形状和尺寸的颗粒组成来减轻料斗排放期间颗粒分离的方法的建议。最后，拟议的研究将通过学生（一名博士生和少数民族本科生研究人员）参与研究，并通过期刊出版物和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.