Granular soils subjected to flow through their soil skeleton can show a behaviour in which fine particles migrate through the pore space between coarser particles. This process is called internal instability or suffusion. This contribution deals with the numerical analysis of the migration of fine particles in a soil column subjected to fluid flow with unresolved coupled computational fluid dynamics–discrete element method (CFD–DEM) with special regards to the used drag force correlation. The contribution investigates the influence of the Schiller–Naumann model and its extension with a voidage term on the migration behaviour of fine particles. The voidage term is further varied with a parameter, which controls the impact of the change of the void fraction on the drag force. It could be observed that the Schiller–Naumann model does not yield in a suffusive behaviour while the extended models show significant particle migration. Thereby, increasing the impact of the void fraction on the drag force results in stronger particle migration. These results reveal the need for good validation techniques. They indicate how the drag force correlation can be adapted to depict the correct particle migration behaviour.

中文翻译：

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空隙率对粒子迁移的影响：关于阻力关系的计算流体动力学-离散元耦合方法研究

流经其土壤骨架的粒状土壤可表现出一种行为，其中细颗粒迁移通过较粗颗粒之间的孔隙。此过程称为内部不稳定或布满。该贡献使用未解决的耦合计算流体动力学离散元方法（CFD-DEM），特别是对所使用的拖曳力相关性，对细颗粒在受流体流动的土壤柱中的迁移进行了数值分析。该贡献调查了席勒-瑙曼模型的影响及其以空隙项的扩展对微粒迁移行为的影响。空隙率还随参数变化，该参数控制空隙率变化对拖曳力的影响。可以观察到，席勒-瑙曼模型没有产生充实的行为，而扩展模型显示出明显的粒子迁移。因此，增加空隙率对拖曳力的影响导致更强的颗粒迁移。这些结果表明需要良好的验证技术。它们表明了如何使阻力相关性适合于描述正确的颗粒迁移行为。