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| 1 | Discrete element simulation of cylindrical particles using super-ellipsoids显示文摘A discrete element model based on super-ellipsoids was used to simulate cylindrical particle flow. The model can describe a cylindrical particle accurately provided the shape indices of the super-ellipsoids are set to appropriate values. To achieve more rapid calculations, we implemented an 'oriented bounding box algorithm'(OBBA) for the initial contact detection of cylindrical particles. Several types of Simulations were performed to validate the super-ellipsoid model and the contact-detection algorithm. First, the effect of shape index of the super-ellipsoids on model accuracy was investigated through three simulations: impact of a cylindrical particle on a flat wall, flow of cylindrical particles in a rotating tumbler, and segregation of cylindrical particles of different length flowing down a bounded heap. The simulation results show that the super-ellipsoids describe cylindrical particles accurately when the shape index that specifies the sharpness of the cylinder edges is sufficiently large. The efficiency of the OBBA is measured by simulations in which a box is filled with cylindrical particles and a tumbler that contains cylindrical particles is rotated. The simulation results show that the OBBA can accelerate the calculations significantly. The effect of particle shape (such as aspect ratio and shape index) on the calculation speed was obtained. The simulation of rod-like particles tended to take more calculation time than that of disk-like particles, and the simulation time increased with an increasing particle-shape index. | Yongzhi Zhao Lei Xu Paul B. Umbanhowar Richard M. Lueptow | 2019 | Particuology2019，17，5： | 12 |
| 2 | 离散单元法及其在流态化领域的应用显示文摘经过三十余年的发展,离散单元法(discrete element method,DEM)已经发展成为一种广泛应用于过程工程领域中颗粒体系研究的数值方法,特别是将DEM与计算流体力学(computational fluid dynamics,CFD)相结合形成的CFD-DEM耦合方法,已经在流态化研究领域得到广泛应用。首先对DEM模型进行了综述,包括DEM模型的基本原理、颗粒形状模型、接触力模型、非接触力模型、流体作用力模型等;然后对CFD-DEM耦合方法及其在流态化领域的一些主要应用进行了介绍,包括在流化床、气力输送以及过程工程领域里的一些其他应用。最后对DEM模型以及CFD-DEM耦合方法的发展趋势进行了预测,希望能促进DEM方法的发展,并推动其在过程工程领域中的应用。 | 周池楼 赵永志 | 2014 | 化工学报2014，65，7： | 10 |
| 3 | 连续操作密相流化床颗粒停留时间分布特性模拟放大研究显示文摘采用基于GPU(graphics processing unit)大规模并行的粗粒化CFD-DEM(computational fluid dynamicsdiscrete element method)方法,耦合多分散、非球形颗粒曳力模型,对连续操作的三维流化床进行了长时间颗粒停留时间模拟。通过对不同尺寸(长度)流化床的模拟发现不同粒径颗粒平均停留时间(mean residence time,MRT)与流化床长度呈线性关系,该关系可以用来预测更大尺寸流化床内的颗粒停留时间。随着流化床长度的增加,不同粒径颗粒MRT的差异变大,说明流化床长度的增加对不同尺寸颗粒的停留时间具有一定的调控能力。 | 兰斌 徐骥 刘志成 王军武 | 2021 | 化工学报2021，72，1： | 8 |
| 4 | Transition of axial segregation patterns in a long rotating drum显示文摘Axial segregation of a bidisperse mixture of particles in a long rotating drum is studied using the discrete element method. Simulation results show that particle interaction is responsible for axial segregation,the patterns of which are influenced by the end wall effect. Axial segregation patterns transform under competing influences of the end walls and the particle interaction forces. The two influential factors vary with various rotational speeds and end wall friction levels. The result is the transition of different axial segregation patterns: two large-particle bands at both ends, two small-particle bands at both ends, or a random segregation pattern where either a large-particle band or small-particle band may appear at either end. | Zequn Cui Yongzhi Zhao Youchuan Chen Xiao Liu Zhengli Hua Chilou Zhou Jinyang Zheng | 2014 | Particuology2014，12，2： | 6 |
| 5 | 提升管内湿颗粒流动特性的离散元模拟显示文摘采用离散单元法模拟了二维提升管内湿颗粒的流动和团聚特性。考虑颗粒所受重力、颗粒间(颗粒与壁面间)的碰撞力、摩擦力、液桥力以及气体对颗粒的曳力和浮力。预测提升管内湿颗粒的流动行为,得到不同含湿量下颗粒浓度和轴向速度的分布,并且定量分析了湿颗粒的团聚特性。结果显示:湿颗粒在提升管内呈现边壁浓、中心稀的环核流动结构;由于液桥力的存在,提升管内湿颗粒出现团聚现象,且颗粒以单颗粒和聚团2种方式运动;含湿量对颗粒聚团存在时间、聚团时间份额和聚团生成频率有较大的影响。 | 朱卫兵 李锦时 王猛 孙巧群 | 2013 | 中国电机工程学报2013，33，35： | 6 |
| 6 | 提升管内气固流动特性的离散元模拟显示文摘采用离散单元法模型对二维提升管内气固流动特性进行了数值模拟。利用标准k-ε模型模拟气相的湍流流动,考虑了颗粒间的van der Waals力和滚动摩擦的作用。通过对颗粒和气体流动行为的分析,得到了颗粒浓度、速度、温度及气体速度等的分布,研究了表观气速和颗粒循环速率对颗粒流动的影响。结果显示:颗粒在提升管内呈现边壁浓、中心稀的环核流动及上稀下浓的流动结构;气固两相都存在一定程度的返混现象;增加表观气速,使颗粒浓度降低、速度增大,颗粒分布更均匀;增加颗粒循环速率,使颗粒浓度增大,而颗粒速度对颗粒循环速率的变化不敏感,颗粒分布的不均匀性更强。模拟结果与文献中实验定性吻合。 | 王猛 朱卫兵 孙巧群 张小彬 周金哲 | 2013 | 化工学报2013，64，7： | 6 |
| 7 | Modeling and simulation of chemically reacting flows in gas-solid catalytic and non-catalytic processes显示文摘This paper gives an overview of the recent development of modeling and simulation of chemically reacting flows in gas-solid catalytic and non-catalytic processes.General methodology has been focused on the Eulerian-Lagrangian description of particulate flows,where the particles behave as the catalysts or the reactant materials.For the strong interaction between the transport phenomena(i.e.,momentum,heat and mass transfer)and the chemical reactions at the particle scale,a cross-scale modeling approach,i.e.,CFD-DEM or CFD-DPM,is established for describing a wide variety of complex reacting flows in multiphase reactors.Representative processes,including fluid catalytic cracking(FCC),catalytic conversion of syngas to methane,and coal pyrolysis to acetylene in thermal plasma,are chosen as case studies to demonstrate the unique advantages of the theoretical scheme based on the integrated particle-scale information with clear physical meanings.This type of modeling approach provides a solid basis for understanding the multiphase reacting flow problems in general. | Changning Wu Binhang Yan Yong Jin Yi Cheng | 2010 | Particuology2010，8，6： | 5 |
| 8 | 快速流化床颗粒团絮特征的MP-PIC数值模拟显示文摘为了研究快速流化床颗粒的团絮特征,建立了基于多相质点网格法的快速流化床气固多相流三维数理模型,气相场采用大涡湍流模型,通过求解牛顿运动方程得到颗粒相运动信息,气固间相互作用力采用Gidaspow曳力模型,固体间作用力通过计算颗粒应力梯度得到。基于该模型,对三维快速流化床上升管(H=3 m、d=0.1 m)气固流动开展了数值模拟,并与实验进行了校正,研究了在气速工况Ug=5.28 m?s-1下的颗粒(ρp=2650 kg?m-3、dp=250μm)团絮性质,实现了对上升管内颗粒团絮的基本类型(条形团絮、马鞍形团絮、U形团絮)的成功预测,并揭示了不同类型团絮在上升管内形成、发展、聚并直至破碎的演化规律。结果表明,上升管径向颗粒团絮的平均颗粒浓度分布呈现中间低两边高的环核结构,颗粒团絮速度的分布与其相反;随着轴向高度的增加,颗粒团絮的颗粒浓度逐渐降低而速度逐渐增加,但达到一定高度后变化减缓。 | 孙子文 陈岱琳 钟文琪 Aibing Yu | 2018 | 化工学报2018，69，8： | 4 |
| 9 | An erosion model for the discrete element method显示文摘 | Yongzhi Zhao Huacling Ma Lei Xu Jinyang Zheng | 2017 | Particuology2017，15，5： | 2 |
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