Collisional flows of oriented granular materials

在这个研究项目中，我们建议开发高精度的非球面取向的颗粒，将用于设计高效的过程，涉及运输和分选这种颗粒状材料的流变模型。高精度的颗粒流变模型已成功地用于许多应用，涉及颗粒加工，但这些模型仅限于球形颗粒忽略了形状和方向的颗粒。然而，天然存在的颗粒状材料由非球形颗粒组成;在采矿业中，在农业和食品加工业中，颗粒具有细长或扁平形状，或者在制药业中，具有药丸和药物胶囊的沙粒，岩石或鹅卵石。这些材料的有效加工依赖于谷物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设计有效加工这些材料的工艺和设备至关重要。该项目开发的模型将为相关学术和工业界提供准确和具有成本效益的计算工具，以模拟和研究加拿大和国际上许多行业中使用的真实颗粒流。 为了实现这些目标，我们将推广颗粒动力学理论模型，这是非常成功地用于模拟碰撞稠密流动的球形颗粒，非球面取向的颗粒。非球面取向晶粒的流动表现出非常复杂的流变响应，因为它是由微观结构的接触和碰撞，并由晶粒的取向和排列。目前，为非球面取向晶粒开发的模式使用由昂贵的经验数据确定的唯象参数。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。该方法能够有效地降低计算成本，为大规模非球面颗粒流的数值模拟提供了有效的工具。

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.