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

CBET 1438077/1435861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。 该项目将调查令人惊讶的观察结果，即在由球形颗粒组成的颗粒状材料中添加少量针状颗粒，显着增加材料的流动能力。 对于非常小的颗粒，研究人员假设针和球以某种方式粘在一起，从而形成有效的颗粒形状和尺寸，使材料更容易流动。对于不太可能粘附的较大颗粒，怀疑有其他润滑机制。将进行一系列的实验，以显示颗粒尺寸和混合比如何影响流动特性。 这些实验将通过数值模拟来补充，这些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。 本项目将为研究生和本科生提供一个参与研究的环境。本项目研究由球形和不规则形状颗粒组成的颗粒混合物的流动和剪切。 实验将进行规范的几何形状，如料斗，圆柱形柱崩溃，和环形库埃特剪切，研究流动行为的颗粒尺寸和混合比的函数。 这些实验将把目前用于量化流动的几个量联系在一起，包括静态和动态休止角、动态偏转模量和流动性指数。 计算机模拟将研究在密集系统的棒和混合物的棒和球的剪切，以揭示增强流动的基本机制，无论是在有效的形态或偏析引起的润滑的变化。

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.