Abstract This study presents an improved VOF-DEM model where the Darcian velocity and a compound variable are treated as unknowns in the pressure-velocity calculation procedure such that the use of interpolated porosity at cell faces is minimised and stability is ensured even if the porosity field is not smooth or even ragged. A higher-order porosity estimation method is also used such that the porosity and interaction force are evaluated correctly when the CFD cell size is of the same order as the DEM particle size. Additionally, a particle size scaling technique is proposed to let the DEM particle size different from the real soil particle size and soil-water interaction forces are the same as when the real soil particle size is used. This is achieved by modifying the calculation of drag force. The solution scheme is verified in two case where analytical solutions exist. Particle size scaling technique is also used and tested in permeability tests and wave interaction with porous structure. Subsequently, the settling and collision of particles in water, dambreak of soil-water mixture and submerged landslides are simulated. With the present improvements and the particle size scaling, the capability of the VOF-DEM is extended in soil-water interaction problems.

中文翻译：

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一种改进的 VOF-DEM 模型，用于土壤-水相互作用与粒度缩放

摘要 本研究提出了一种改进的 VOF-DEM 模型，其中 Darcian 速度和复合变量在压力-速度计算过程中被视为未知数，从而最大限度地减少了单元面插值孔隙率的使用，即使孔隙率场也能确保稳定性不光滑甚至参差不齐。还使用了高阶孔隙率估计方法，以便在 CFD 单元尺寸与 DEM 粒度处于同一数量级时正确评估孔隙率和相互作用力。此外，提出了一种粒度缩放技术，使 DEM 粒度与实际土壤粒度不同，土壤-水相互作用力与使用实际土壤粒度时相同。这是通过修改阻力的计算来实现的。求解方案在存在解析解的两种情况下得到验证。在渗透性测试和波与多孔结构的相互作用中也使用和测试了粒度缩放技术。随后，模拟了颗粒在水中的沉降和碰撞、土水混合物的溃坝和淹没的滑坡。随着目前的改进和粒度缩放，​​VOF-DEM 在土壤-水相互作用问题中的能力得​​到了扩展。