Collaborative Research: Enhanced Flow and Shear of Irregular Grains and Powders

CBET 1438077/1435861该奖项支持对由颗粒混合物组成的颗粒材料流动的实验和计算研究。该项目将调查这一令人惊讶的观察结果，即在由球形颗粒组成的颗粒材料中添加少量针状颗粒显著提高材料的流动能力。对于非常小的颗粒，研究人员假设针头和球体粘在一起的方式导致了有效的颗粒形状和大小，使材料更容易流动。对于较大的颗粒不太可能粘在一起，可能存在其他润滑机制。将进行一系列实验，以展示颗粒尺寸和混合比对流动特性的影响。这些实验将得到数值模拟的补充，数值模拟可以预测颗粒的排列，并将颗粒排列与定义明确的模型流中的流动行为相关联。该项目将为研究生和本科生提供一个参与研究的环境。该项目研究由球形和不规则形状的颗粒组成的混合颗粒的流动和剪切。实验将采用典型的几何形状，如料斗、圆柱体坍塌和环形库埃特剪切，以研究颗粒尺寸和混合比对流动行为的影响。这些实验将把目前用于定量流动的几个量联系在一起，包括静态和动态休止角、动态偏转模数和流动性指数。计算机模拟将研究稠密的棒材体系以及棒材和球体混合物中的剪切，以揭示强化流动的基本机制，无论是有效形态的变化还是偏析诱导的润滑。

CBET 1438077/1435861This award supports experimental and computational studies of the flow of granular materials composed of mixtures of particles. The project will investigate the surprising observation that adding a small number of needle-like particles in a granular material composed of spherical particles significantly increases the ability of the material to flow. For very small particles, the investigators hypothesize that the needles and spheres stick together in a way that results in an effective particle shape and size that enables the material to flow more easily. For larger particles less likely to adhere, other lubrication mechanisms are suspected. A series of experiments will be conducted to show how the particle size and the mixture ratio affects flow characteristics. The experiments will be complemented by numerical simulations that can predict the arrangements of particles and correlate particle arrangements with flow behavior in well-defined model flows. The project will provide an environment for graduate and undergraduate students to participate in the research.This project studies the flow and shear of mixtures of particles consisting of spherical and irregularly-shaped particles. Experiments will be conducted with canonical geometries, such as hoppers, cylindrical column collapse, and annular-Couette shear, to study the flow behavior as functions of particles size and mixture ratio. The experiments will tie together several quantities currently used to quantify flow, including the static and dynamic angles of repose, dynamic deflection modulus and flowability index. Computer simulations will study shear in dense systems of rods and mixtures of rods and spheres to reveal the fundamental mechanisms for enhanced flow whether it is changes in the effective morphology or segregation-induced lubrication.