scholarly journals Critical time step for discrete element method simulations of convex particles with central symmetry

Author(s):  
Di Peng ◽  
Shane J. Burns ◽  
Kevin J. Hanley
Clean Energy ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 141-166
Author(s):  
Bing Liu

Abstract An algorithm using the discrete element method (DEM) for simulating the particulate behaviour of flow and heat transfer is developed and described, the reasonable hypothesis and the ingenious design of which have been presented in detail. The organizational structure of the developed algorithm contains an efficient method for determining particle collisions, the status analysis for each particle and the particulate-kinematics analysis during the time step. The reasonability and correctness of the developed DEM algorithm are validated by laboratory experiments: the discharge process of glass beads from a silo; and heating of metal alloy particles in a calciner. Afterwards, a group of validated mechanics parameter values for coal and sand have been tested and verified in the article, preparing for the simulation of the pyrolysis process in a downer or screw reactor in subsequent research projects.


2014 ◽  
Vol 31 (4) ◽  
pp. 810-823 ◽  
Author(s):  
Zheng Lu ◽  
Xilin Lu ◽  
Huanjun Jiang ◽  
Sami F. Masri

Purpose – The particle damper is an efficient vibration control device and is widely used in engineering projects; however, the performance of such a system is very complicated and highly nonlinear. The purpose of this paper is to accurately simulate the particle damper system properly, and help to understand the underlying physical mechanics. Design/methodology/approach – A high-fidelity simulation process is well established to account for all significant interactions among the particles and with the host structure system, including sliding friction, gravitational forces, and oblique impacts, based on the modified discrete element method. In this process, a suitable particle damper system is modeled, reaction forces between particle aggregates and the primary structure are incorporated, a reasonable contact force model and time step are determined, and an efficient contact detection algorithm is adopted. Findings – The numerical results are further validated by both special computational tests and shaking table tests, with good agreements to the experimental results. The method is shown to be effective and accurate to simulate the particle damper system. Originality/value – The approaches described in this paper provide an efficient numerical way to investigate complex particle damper systems.


TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.


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