Collaborative Research: Hybrid Discrete-Continuum Numerical Simulation of Granular Materials

颗粒物料的流动在许多制造过程中都很重要，特别是在制药、能源和农业工业中，以及在雪崩、滑坡和沉积物运输等自然发生的过程中。对流动颗粒材料的行为进行建模是具有挑战性的，因为流动材料的可观察可测量特性取决于材料单个颗粒尺度上的微观动力学。在缺乏可靠模型的情况下，处理颗粒物料的设备设计通常基于启发式方法，这不是最优的，偶尔会导致灾难性的故障。该奖项将支持预测颗粒系统动力学的新框架，同时解决小规模和大规模现象。新的框架将是一种混合方法，将颗粒材料作为流体的模型与颗粒材料作为离散颗粒集合的模型相结合。将解决的关键挑战是找到合适的方法将这些方法结合在一个混合模型中，该模型可以准确地模拟定义良好的原型颗粒流动，并通过与工业和地质尺度颗粒流动现象的比较进行验证。项目中生成的计算机代码将公开共享，研究团队将邀请不同学术水平的学生参与该项目，特别是来自传统上代表性不足的群体的学生。将开发一种模拟颗粒流动的混合框架，以获得宏观尺度连续体模拟的效率和微观尺度离散颗粒模拟的准确性和精度。杂交方案的四个组成部分将被探索：一个耦合过程，沿着调和区机械地握手连续统制度和粒子制度，一个均匀化算子，用连续状态取代离散元素区，一个富集算子，在相反的方向，以及一个oracle，确定在哪里是安全的，在哪里需要富集到离散颗粒。该方案的组成部分将根据分析结果和实验数据分别进行测试和验证。整个混合模型将针对大规模颗粒现象进行验证，目标是精确模拟工业和地理尺度的流动。这项工作的结果及其相关的计算机代码将提供给工业和地球科学的从业人员和研究人员以及颗粒流动现象的电影实现的开发人员。

CBET - 1706689PI: Grinspun, EitanThe flow of granular materials is important in many manufacturing processes, especially in the pharmaceutical, energy, and agricultural industries, and in naturally-occurring processes such as avalanches, landslides and sediment transport. Modeling the behavior of flowing granular materials is challenging because observable measurable properties of the flowing material depend on microscopic dynamics on the scale of the individual grains of the material. In the absence of reliable models, the design of equipment to handle granular materials is often based on heuristic approaches, which are not optimal and occasionally lead to catastrophic failures. This award will support a new framework for predicting the dynamics of granular systems that addresses small-scale and large-scale phenomena at the same time. The new framework will be a hybrid approach that combines models of granular materials as fluids with models of granular materials as collections of discrete particles. The key challenge that will be addressed is to discover the appropriate way to combine these approaches in a hybrid model that accurately simulates well-defined prototype granular flows and is validated against comparisons with industrial and geological scale granular flow phenomena. Computer codes that are generated in the project will be shared publicly, and the research team will engage students at various academic levels to participate in the project, especially students from traditionally underrepresented groups.A hybrid framework for simulating granular flows will be developed to obtain the efficiency of continuum simulations at the macroscale and the accuracy and precision of discrete particle simulations offer at the microscale. Four components of the hybridization scheme will be explored: a coupling procedure that mechanically handshakes the continuum regime and the particle regime along a reconciliation zone, a homogenization operator that replaces a discrete element zone with a continuum state, an enrichment operator that acts in the opposite direction, and an oracle that determines where it is safe to homogenize and where enrichment to discrete grains is needed. Components of the scheme will be separately tested and validated against analytical results and experimental data. The overall hybrid model will then be validated against large-scale granular phenomena with the goal of accurately simulation flows up to the industrial- and geo-scales. The results of this work and its associated computer codes will be made available to practitioners and researchers in industry and geosciences and to developers of cinematic realizations of granular flow phenomena.