Collisional flows of oriented granular materials

在这个研究项目中，我们建议为非球面定向颗粒开发高度精确的流变模型，该模型将用于设计涉及此类颗粒材料的运输和分选的有效过程。高精度的颗粒流变模型已经成功地用于许多涉及颗粒加工的应用，但这些模型仅限于球形颗粒，忽略了颗粒的形状和方向。然而，自然产生的颗粒材料是由非球形颗粒组成的；砂粒，岩石，或鹅卵石在采矿业，在农业和食品加工业中，谷物有细长或扁平的形状，或在制药药丸和药物胶囊。这些材料的有效加工依赖于颗粒的稳定流动和避免堵塞。因此，非球面取向晶粒的高精度流变模型的可用性对于有效加工这些材料的工艺和设备的设计至关重要。该项目开发的模型将为相关学术界和工业界提供准确和经济有效的计算工具，以模拟和研究现实的颗粒流动，这在加拿大和国际上的许多行业中都得到了应用。为了实现这些目标，我们将颗粒动力学理论模型推广到非球面取向颗粒，这些模型非常成功地用于模拟球形颗粒的碰撞密集流动。非球面取向晶粒的流动受微观结构的接触和碰撞以及晶粒的取向和排列控制，表现出非常复杂的流变响应。目前，非球面取向晶粒的模式使用的是由昂贵的经验数据确定的现象学参数。然而，这些参数可以通过使用动力学理论直接确定，避免使用昂贵的实验或微观计算机模拟。降低所需成本的能力将为模拟大规模非球面定向颗粒流提供高效和有效的工具。

In this research project we propose to develop highly accurate rheological models for aspherical oriented grains that will be used to design efficient processes involving transportation and sorting of such granular materials. Highly accurate rheological models for grains have been successfully used for many applications involving granular processing, yet these models are limited to spherical grains ignoring the shape and orientations of the grains. However, naturally occurring granular materials are composed of aspherical particles; sand particles, rocks, or pebbles in the mining sector, in the agriculture and food processing industries where grains have elongated or flattened shapes, or in pharmaceutics with pills and drug capsules. The efficient processing of these materials relays on steady flow of the grains and avoiding jamming. Hence, availability of highly accurate rheological models for aspherical oriented grains is essential for the design of processes and equipment to efficiently process these materials. The models developed in this project will provide accurate and cost-effective computational tools to the related academic and industrial communities to simulate and study realistic granular flows, which are used in many industries in Canada and internationally. To achieve these goals, we will generalize the granular kinetic theory models, which are very successfully used to model collisional dense flows of spherical grains, to aspherical oriented grains. The flow of aspherical oriented grains shows a very complex rheological response as it is governed by the microstructure contact and collision and by the orientation and alignment of the grains. Currently, the modes developed for aspherical oriented grains use phenomenological parameters that are determined by costly empirical data. However, these parameters can be determined directly by using kinetic theory, avoiding the use of expensive experiments or microscopic computer simulations. The ability to reduce the required cost will provide efficient and effective tool to simulate large-scale aspherical oriented granular flows.