Study on a large-scale discrete element model for fine particles in a fluidized bed

2012 ◽  
Vol 23 (5) ◽  
pp. 673-681 ◽  
Author(s):  
Mikio Sakai ◽  
Hiroyuki Takahashi ◽  
Christopher C. Pain ◽  
John-Paul Latham ◽  
Jiansheng Xiang
Keyword(s):  
Fluidized Bed ◽  
Large Scale ◽  
Fine Particles ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model

scholarly journals Vertical grain size sorting in bedload transport on steep slopes with a coupled fluid-discrete element model

2018 ◽  
Vol 40 ◽  
pp. 04013
Author(s):  
Philippe Frey ◽  
Rémi Chassagne ◽  
Raphaël Maurin ◽  
Julien Chauchat
Keyword(s):  
Grain Size ◽  
Fine Particles ◽  
Element Model ◽  
Discrete Element ◽  
Bedload Transport ◽  
Initial Time ◽  
Discrete Element Model ◽  
Size Sorting ◽  
Bedload Sediment ◽  
Particle Bed

In order to study vertical grain size sorting in bedload sediment transport, numerical experiments of two-size particle mixtures were carried out, using a validated coupled fluid-discrete element model developed at Irstea. A 3D 10% steep domain, consisting at initial time of a given number of layers of 4 mm particles deposited on top of a coarser 6 mm particle bed, was sheared by a turbulent and supercritical fluid flow (Shields numbers of 0.1 and 0.3). The elevation of the centre of mass of the infiltrated fine particles is observed to follow the same logarithmic decrease with time, whatever the initial number of fine layers. This decrease is steeper for a higher Shields number. The main result is that this typical behaviour is related at first order to the particle shear rate depth profile.

scholarly journals Impact of Ballast Fouling on the Mechanical Properties of Railway Ballast: Insights from Discrete Element Analysis

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1331
Author(s):  
Luyu Wang ◽  
Mohamed Meguid ◽  
Hani S. Mitri
Keyword(s):  
Shear Strength ◽  
Mechanical Response ◽  
Fine Particles ◽  
Element Model ◽  
Discrete Element ◽  
Shear Loading ◽  
Discrete Element Model ◽  
Railway Ballast ◽  
Fouled Ballast ◽  
Interparticle Friction

Ballast fouling is a major factor that contributes to the reduction of shear strength of railway ballast, which can further affect the stability of railway supporting structure. The major sources of ballast fouling include infiltration of foreign fines into the ballast material and ballast degradation induced by train movement on the supported tracks. In this paper, a discrete element model is developed and used to simulate the shear stress–strain response of fouled ballast assembly subjected to direct shear loading. A simplified computational approach is then proposed to model the induced ballast fouling and capture the mechanical response of the ballast at various levels of contamination. The approach is based on the assumption that fine particles comprising the fouling material will not only change the interparticle friction angle, but also the contact stiffness between the ballast particles. Therefore, both the interparticle friction coefficient and effective modulus are adjusted based on a fouled ballast model that is validated using experimental results. The effect of ballast degradation is also investigated by gradually changing the particle size distribution of the ballast assembly in the discrete element model to account for the increased range of particle sizes. Using the developed model, the effect of ballast degradation on the shear strength is then evaluated. Conclusions are made to highlight the suitability of these approximate approaches in efficiently modeling ballast assemblies under shear loading conditions.

scholarly journals Novel fluid grid and voidage calculation techniques for a discrete element model of a 3D cylindrical fluidized bed

2014 ◽  
Vol 65 ◽  
pp. 18-27 ◽  
Author(s):  
Christopher M. Boyce ◽  
Daniel J. Holland ◽  
Stuart A. Scott ◽  
John S. Dennis
Keyword(s):  
Fluidized Bed ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model

scholarly journals Discrete element model for general polyhedra

2021 ◽  
Author(s):  
Alfredo Gay Neto ◽  
Peter Wriggers
Keyword(s):  
Frictional Contact ◽  
Virtual Work ◽  
Particle Surface ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Principle Of Virtual Work ◽  
Dynamics Model ◽  
Railway Ballast ◽  
Multibody Dynamics Model

AbstractWe present a version of the Discrete Element Method considering the particles as rigid polyhedra. The Principle of Virtual Work is employed as basis for a multibody dynamics model. Each particle surface is split into sub-regions, which are tracked for contact with other sub-regions of neighboring particles. Contact interactions are modeled pointwise, considering vertex-face, edge-edge, vertex-edge and vertex-vertex interactions. General polyhedra with triangular faces are considered as particles, permitting multiple pointwise interactions which are automatically detected along the model evolution. We propose a combined interface law composed of a penalty and a barrier approach, to fulfill the contact constraints. Numerical examples demonstrate that the model can handle normal and frictional contact effects in a robust manner. These include simulations of convex and non-convex particles, showing the potential of applicability to materials with complex shaped particles such as sand and railway ballast.

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