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

该奖项支持由颗粒混合物组成的颗粒材料流动的实验和计算研究。该项目将研究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可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以某种方式粘在一起，产生有效的颗粒形状和大小，使材料更容易流动。对于不太可能粘附的较大颗粒，可能存在其他润滑机制。将进行一系列的实验，以显示颗粒大小和混合比例如何影响流动特性。实验将辅以数值模拟，可以预测颗粒的排列，并将颗粒排列与良好定义的模型流中的流动行为联系起来。该项目将为研究生和本科生提供参与研究的环境。本课题研究由球形颗粒和不规则形状颗粒组成的颗粒混合物的流动和剪切。实验将采用典型的几何形状，如漏斗、圆柱柱崩塌和环形库埃特剪切，来研究颗粒大小和混合比的流动行为。实验将结合目前用于量化流动的几个量，包括静态和动态休止角，动态偏转模量和流动性指数。计算机模拟将研究密集系统中的棒和棒与球的混合物中的剪切，以揭示增强流动的基本机制，无论是有效形态的变化还是分离诱导的润滑。

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.