UNS: Controlling mixing and segregation of granular media using unsteady flows

CBET -1511450 PI：Umbanhowar，Paul颗粒状材料如沙子、雪和盐由大量固体颗粒组成，这些颗粒主要通过接触焦点相互作用。 流动的颗粒状材料出现在自然现象中，如滑坡和雪崩，以及工业过程中，如制药和矿石加工。 当颗粒在尺寸、密度、粗糙度或一些其他物理特性上彼此不同时，它们可能在流动期间分离，这使加工复杂化并降低产品质量。 该项目的目标是发现避免或减少分离的方法，并改善不稳定颗粒流中的混合，即随时间变化的流动。 该项目涉及实验，以确定如何流量调制可以最好地控制偏析和混合的材料组成的各种尺寸的颗粒。这些实验将通过建模和计算机模拟来补充，这可以帮助解释结果并预测控制偏析的最佳调制方法。 结果将产生有用的处理方法和建模工具，为工业从业者。 该项目团队将由来自代表性不足的群体和当地高中的学生组成，研究非稳态运动学和分离之间的相互作用，以开发一个基于连续介质的框架来预测多分散颗粒在有界堆流和旋转堆流中的空间颗粒分离分布。 结果将被用来证明如何流量调制，如进料速度的变化，在堆流或旋转速度的变化，可以抑制分离和改善混合。 该项目的研究结果将通过提供适用于各种操作条件并由基于连续体的模型支持的方法来指导工业颗粒材料工艺和系统。该模型将考虑不稳定流动，偏析，碰撞扩散，所有这些都是重要的元素，在广泛的颗粒过程。 实验和模拟的结合将提供一个扩展和改进的理解流动，分离，混合和图案形成颗粒系统。

CBET - 1511450PI: Umbanhowar, PaulGranular materials such as sand, snow, and salt consist of large numbers of solid particles that interact with each other primarily through contact foces. Flowing granular materials occur in natural phenomena, such as landslides and avalanches, and in industrial processes, such as pharmaceutical manufacturing and ore processing. When the particles differ from each other in size, density, roughness or some other physical characteristic, they can segregate during flow, which complicates processing and diminishes product quality. The goal of this project is to discover ways to avoid or reduce segregation and improve mixing in unsteady granular flows, i.e. flows that vary in time. The project involves experiments to determine how flow modulation can best control segregation and mixing for materials consisting of particles of various sizes. The experiments will be complemented by modeling and computer simulation that can help interpret the results and predict optimal modulation methods for controlling segregation. Results will generate useful processing methods and modeling tools for industrial practitioners. The project team will comprise a diverse group of researchers and students, including students from underrepresented groups and local high schools.The project will examine the interplay between unsteady kinematics and segregation to develop a continuum-based framework to predict spatial particle segregation distributions for polydisperse particles in bounded heap flow and rotating tumbler flow. The results will be used to demonstrate how flow modulations, such as feed rate variations in heap flow or rotational speed variations in tumbler flow, can inhibit segregation and improve mixing. Findings from the project will guide industrial granular materials processes and systems by providing methodologies that apply over a wide range of operating conditions and that are supported by a continuum-based model. The model will account for unsteady flow, segregation, and collisional diffusion, all of which are important elements in a broad array of granular processes. The combination of experiments and simulations will provide an expanded and improved understanding of flow, segregation, mixing and pattern formation in granular systems.