In recent decades, growing efforts have been devoted to coupling the Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM), i.e., CFD-DEM coupling methods, to account for particle–fluid interactions. However, it remains a challenging task for the well-known Immersed Boundary Method (IBM) belonging to the resolved CFD-DEM methods to improve the computational efficiency of large particles occupying several fluid cells and to simulate the interactions between irregularly shaped particles and fluids. In this paper, we present a novel unresolved CFD-DEM method to achieve the end. The main idea of the presented method is to split a large particle into multiple small spherical particles without overlapping using the Bonded-Particle Method (BPM), and simulate the particle–fluid interactions based on each small particle in the context of an unresolved CFD-DEM method. We validate the accuracy and efficiency of the novel method by comparing our numerical results of spherical particles in viscous fluids with those calculated using the IBM and existing experimental data. The presented method is further applied to the irregular large particle–fluid interaction problems, and the numerical results demonstrate the capacity of our method in simulating the motions of nonspherical large particles in the fluid.

中文翻译：

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大颗粒与流体相互作用模拟的未解析 CFD-DEM 方法的开发

近几十年来，越来越多的努力致力于耦合计算流体动力学 (CFD) 和离散元方法 (DEM)，即 CFD-DEM 耦合方法，以解释粒子-流体相互作用。然而，对于属于已解析 CFD-DEM 方法的著名浸入边界方法 (IBM) 来说，提高占据多个流体单元的大粒子的计算效率并模拟不规则形状的粒子与流体之间的相互作用仍然是一项具有挑战性的任务。在本文中，我们提出了一种新的未解决的 CFD-DEM 方法来实现这一目标。所提出方法的主要思想是使用键合粒子方法（BPM）将一个大粒子分成多个小球形粒子而不重叠，并在未解析的 CFD-DEM 方法中基于每个小粒子模拟粒子-流体相互作用。我们通过将粘性流体中球形颗粒的数值结果与使用 IBM 和现有实验数据计算的结果进行比较，验证了新方法的准确性和效率。所提出的方法进一步应用于不规则的大粒子-流体相互作用问题，数值结果证明了我们的方法在模拟流体中非球形大粒子运动的能力。