加拿大不列颠哥伦比亚大学Sanja Miskovic课题组用全耦合CFD-DEM-VOF方法，分析了大颗粒入水过程中的颗粒分散和空腔形成。相关论文于2024年1月22日发表在《颗粒学报》杂志上。

该文提出了一种完全耦合的计算流体动力学-离散元法-流体体积(CFD-DEM-VOF)模型的发展和验证，以模拟具有自由表面的粒子负载流动的复杂行为。流体和颗粒相之间的耦合是通过实现连续性、动量和α输运方程来建立的。耦合颗粒力，如阻力、压力梯度、稠密虚拟质量、粘滞力和界面力也被集成，阻力和稠密虚拟质量力依赖于局部孔隙度。积分保守α输运方程确保在粒子和水之间的相互作用相体积守恒。

此外，小组还实现了一种设计用于非结构化六面体网格的三线性插值方法。在数值模拟中，该方法已被证明能够很好地解决耦合效应，特别是在相对较小的单元尺寸比的情况下。通过单粒子入水、粒子溃坝和粒子群入水三种不同的试验案例对模型进行了验证。为了研究一组粒子的入水动力学，建立了实验装置，分析了三个关键的流动特征:平均粒子速度、空腔形状和粒子在水中的弥散云剖面的演变。

测试涉及不同的场景，包括两种不同的水位(16.1和20.1厘米)和两种不同的颗粒密度(2650和4000 kg/m³)。实验数据采集采用高速视频测量和粒子跟踪测速(PTV使用ImageJ/TrackMate)方法。结果表明，数值计算结果与理论预测和实验数据吻合良好。

该研究强调了涡旋在空腔形成和粒子弥散中的重要意义。经过验证的CFD-DEM-VOF模型是模拟含颗粒流体流动的最佳工具，有助于深入了解颗粒与流体之间复杂的相互作用。

附：英文原文

Title: Analysis of particle dispersion and cavity formation during bulk particle water entry using fully coupled CFD-DEM-VOF approach

Author: anonymous

Issue&Volume: 2024/01/22

Abstract: This paper presents the development and validation of a fully coupled Computational Fluid Dynamics - Discrete Element Method - Volume of Fluid (CFD-DEM-VOF) model to simulate the complex behavior of particle-laden flows with free surfaces. The coupling between the fluid and particle phases is established through the implemented continuity, momentum, and alpha transport equation. The coupled particle forces such as drag, pressure gradient, dense virtual mass, viscous, and interface forces are also integrated, with drag and dense virtual mass forces being dependent on local porosity. The integrated conservative alpha transport equation ensures phase volume conservation during interactions between particles and water. Additionally, we have implemented a trilinear interpolation method designed to operate on unstructured hexahedral meshes. This method has been tested for its ability to properly resolve the coupling effects in the numerical simulations, particularly in cases with a relatively low cell-size ratio. The model is validated through three distinct test cases: single particle water entry, dam break with particles, and water entry of a group of particles case. The experimental setup is built to study the dynamics of the water entry of a group of particles, where three key flow features are analyzed: the evolution of average particle velocity, cavity shape, and particle dispersion cloud profiles in water. The tests involve four different scenarios, including two different water levels (16.1 and 20.1 cm) and two different particle densities (2650 and 4000 kg/m3). High-speed videometry and Particle Tracking Velocimetry (PTV using ImageJ/TrackMate) methods are employed for experimental data acquisition. It is demonstrated that numerical results are in excellent agreement with theoretical predictions and experimental data. The study highlights the significance of vortices in cavity shaping and particle dispersion. The validated CFD-DEM-VOF model constitutes a robust tool for simulating particle-laden flows, contributing valuable insights into the complex interplay between particles and fluids.

DOI: 10.1016/j.partic.2023.12.018

Source: https://www.sciencedirect.com/science/article/abs/pii/S1674200124000105