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  • Open Access


    Comparison of Coarse Graining DEM Models Based on Exact Scaling Laws

    Bin Zhang1,2, Yiming Huang3,4, Tingting Zhao5,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.3, pp. 1133-1150, 2021, DOI:10.32604/cmes.2021.016018

    Abstract The simulation of a large number of particles requires unacceptable computational time that is the most critical problem existing in the industrial application of the DEM. Coarse graining is a promising approach to facilitate the application of DEM to industrial problems. While the current coarse graining framework is often developed in an ad-hoc manner, leading to different formulations and different solution accuracy and efficiency. Therefore, in this paper, existing coarse graining techniques have been carefully analysed by the exact scaling law which can provide the theory basis for the upscaling method. A proper scaling rule for the size of particles… More >

  • Open Access


    Discrete Element Modelling of Dynamic Behaviour of Rockfills for Resisting High Speed Projectile Penetration

    Tingting Zhao1, Y. T. Feng2,*, Jie Zhang1, Zhihua Wang1, Zhiyong Wang1

    CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.2, pp. 721-735, 2021, DOI:10.32604/cmes.2021.015913

    Abstract This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour of rockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by the Minkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowski overlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternion based orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures a robust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviour of a… More >

  • Open Access


    Discrete Element Simulation of Asphalt Pavement Milling Process to Improve the Utilization of Milled Old Mixture

    Jianmin Wu*, Bingbing Zhang, Chunsheng Wu, Zhiqiang Shu, Shaoqing Li, Jianqi Yang

    Journal of Renewable Materials, Vol.9, No.5, pp. 993-1011, 2021, DOI:10.32604/jrm.2021.014304

    Abstract In order to improve the utilization of milling materials, save stone resources and reduce milling energy consumption, the aged Styrene-butadiene-styrene (SBS) modified asphalt was used as a binder to prepare AC-16 asphalt mixture to simulate old asphalt pavement materials. First, the test and discrete element simulation results of uniaxial compression tests were used to calibrate the parameters of the parallel bonding contact model between asphalt mortar and aggregates. On this basis, a microscopic model of the asphalt mixture was established to simulate the old asphalt pavement. Then, the discrete element software PFC (Particle Flow Code) was used to simulate the… More >

  • Open Access


    Numerical Modelling of Proppant Transport in Hydraulic Fractures

    Yatin Suri1, Sheikh Zahidul Islam1, *, Mamdud Hossain1

    FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.2, pp. 297-337, 2020, DOI:10.32604/fdmp.2020.08421

    Abstract The distribution of proppant injected in hydraulic fractures significantly affects the fracture conductivity and well performance. The proppant transport in thin fracturing fluid used during hydraulic fracturing in the unconventional reservoirs is considerably different from fracturing fluids in the conventional reservoir due to the very low viscosity and quick deposition of the proppants. This paper presents the development of a threedimensional Computational Fluid Dynamics (CFD) modelling technique for the prediction of proppant-fluid multiphase flow in hydraulic fractures. The proposed model also simulates the fluid leak-off behaviour from the fracture wall. The Euler-Granular and CFD-Discrete Element Method (CFD-DEM) multiphase modelling approach… More >

  • Open Access


    Discrete Modelling of Capillary Mechanisms in Multi-Phase Granular Media

    L. Scholtès1, B. Chareyre2, F.Nicot3, F. Darve4

    CMES-Computer Modeling in Engineering & Sciences, Vol.52, No.3, pp. 297-318, 2009, DOI:10.3970/cmes.2009.052.297

    Abstract A numerical study of multi-phase granular materials based upon micro-mechanical modelling is proposed. Discrete element simulations are used to investigate capillary induced effects on the friction properties of a granular assembly in the pendular regime. Capillary forces are described at the local scale through the Young-Laplace equation and are superimposed to the standard dry particle interaction usually well simulated through an elastic-plastic relationship. Both effects of the pressure difference between liquid and gas phases and of the surface tension at the interface are integrated into the interaction model. Hydraulic hysteresis is accounted for based on the possible mechanism of formation… More >

  • Open Access


    Face stability of shallow shield tunnels in dry sandy ground: model tests, discrete element method simulations and theoretical model

    Renpeng Chen, Linggang kong, Lvjun Tang, Yunmin Chen

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.4, pp. 99-100, 2011, DOI:10.3970/icces.2011.020.099

    Abstract Face stability is critical in the underground tunneling. In this report, large-scale model tests on the face stability of shallow tunnels for various cover depths (C/D = 0.5, 1, and 2) in dry sandy ground were firstly introduced. Then, a series of three-dimensional DEM models were built to simulated the process of tunnel face failure. The results of the model tests and DEM simulations reveal that a chimney like failure zone appears during the tunnel face failure. It was founded that with the increase of the horizontal displacement of the tunnel face, the support pressure decreases to the limit support… More >

  • Open Access


    A New Combined Scheme of Discrete Element Method and Meshless Method for Numerical Simulation of Impact Problems

    Li Shan, Ming Cheng, Kaixin Liu

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.3, pp. 87-88, 2011, DOI:10.3970/icces.2011.019.087

    Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is estabilished for modeling the elastoplastic behavior of solid materials. A failure criterion is introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from continuum to discontinuum. In addition, a meshless interpolation… More >

  • Open Access


    Flow Characteristics of Non-Spherical Particles Simulated with Super-Quadric DEM

    Shunying Ji*, Siqiang Wang

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.1, pp. 94-94, 2019, DOI:10.32604/icces.2019.04805

    Abstract Granular flow is commonly encountered in industry or nature, and is significantly affected by particle shapes. Super-quadric particles which can construct the geometric shape of irregular particles are simulated by the Discrete Element Method (DEM). In this study, the influence of aspect ratio and blockiness of particles on the flow characteristics is investigated, and the different discharge angles are used for different shaped particles to show the superposed effect of hopper configuration. Meanwhile, the Lacey mixing index is used to explore the effects of particle shapes on the mixing and motion of the granular system in a horizontal rotating drum.… More >

  • Open Access


    Dynamic Instability of Straight Bars Subjected to Impulsive Axial Loads Using the DEM

    Letícia Fleck Fadel Miguel1, Leandro Fleck Fadel Miguel2, João Kaminski Jr.3

    CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.2, pp. 87-104, 2015, DOI:10.3970/cmes.2015.104.086

    Abstract Since the half of the XX century, attention was given to the instability of structures under parametric excitation, especially under periodic loads. On the other hand, the instability of bars subjected to axial loads of impulsive type has been little studied, in spite of the practical importance of the topic. Thus, in Engineering Design it is frequently supposed, without tests or additional verifications, that an axial load of short duration can exceed the Euler critical load of the bar without inducing damage in the same.
    Within this context, this paper proposes the use of the truss-like Discrete Element Method… More >

  • Open Access


    Design Evaluation of a Particle Bombardment System Used to Deliver Substances into Cells

    Eduardo M. B. Campello1,2, Tarek I. Zohdi3

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.2, pp. 221-245, 2014, DOI:10.3970/cmes.2014.098.221

    Abstract This work deals with the bombardment of a stream of particles possessing varying mean particle size, velocity and aspect ratio into a cell that has fixed (known) compliance characteristics. The particles are intended to penetrate the cell membrane causing zero or minimum damage and deliver foreign substances (which are attached to their surfaces) to the interior of the cell. We adopt a particle-based (discrete element method) computational model that has been recently developed by the authors to describe both the incoming stream of particles and the cell membrane. By means of parametric numerical simulations, treating the stream’s mean particle size,… More >

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