Review: Calibration of the discrete element method

The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade. This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years. Different aspects of tribology that have been reviewed including lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology. This review attempts to highlight recent research and also presents future outlook pertaining to these aspects. It may however be noted that there are limitations of this review. One of the most important of these is that tribology being a highly multidisciplinary field, the research results are widely spread across various disciplines and there can be omissions because of this. Secondly, the topics dealt with in the field of tribology include only some of the salient topics (such as lubrication, wear, surface engineering, biotribology, high temperature tribology, and computational tribology) but there are many more aspects of tribology that have not been covered in this review. Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.

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A review of recent advances in tribology

As a consequence of increasing computer power and more readily useable commercial and open source codes, Discrete Element Method (DEM) is becoming widely used across a range of applications to simulate increasingly complex processes. This is exacerbating the challenge of setting up simulations for industrial applications. The literature on input parameter selection is divided. A number of papers report methods for their direct measurement. Others, by contrast, propose a “calibration” approach where the particle properties are derived as adjustable parameters by quantitative comparison of experimental and simulation results. This paper reports on the calibration and validation of the input parameters for the specific case of cylindrical tablets represented by conjoined spheres. The initial steps are to not only assign and optimise the DEM input parameters but also optimise the shape representation; what degree of linearity of the edges and angularity of the corners are required to accurately reflect the cylindrical shape. The model was used to simulate two configurations of a rotating drum: an “attrition tester” with a single longitudinal baffle and an un-baffled drum. The results were compared qualitatively and quantitatively with experimental data. While the qualitative comparison was good in most cases, detailed quantitative comparison fared less well, with some significant errors. This study highlights some of the key issues for a wider-spread of industrial applications for DEM.

https://www.jstage.jst.go.jp/article/kona/32/0/32_2015016/_pdf

Discrete Element Method (DEM) for Industrial Applications: Comments on Calibration and Validation for the Modelling of Cylindrical Pellets

CFD-DEM modelling and simulation of pneumatic conveying: A review

The influence of particle shape on flow modes in pneumatic conveying

Development of new analysis methods for the characterization and classification of wet sticky ores

The pressure drop predictions across a bypass pipeline in dense phase pneumatic conveying were investigated numerically. The simulation was conducted using the commercial Computational Fluid Dynamic (CFD) software Fluent with the Euler- Euler model accounting for four-way coupling. Experiments and calculations were conducted using flyash powder conveyed in a horizontal pipeline. The influence of the pipe length on pressure drop prediction was also investigated. The results indicate that pressure prediction of the CFD simulation model for a bypass pipe is promising. The conclusion is that this investigation can offer improved insight and initial design modelling capability for bypass pneumatic conveying systems.

CFD Simulation of Gas-Solid Flow in Dense Phase Bypass Pneumatic Conveying Using the Euler-Euler Model

As iron ore deposits are depleted at the face of the mine site, deeper excavation is required to meet the requirements of the supplier. During this deeper excavation, increasing clay and moisture content leads to wet and sticky material (WSM). WSM's are prone to cause problems in all phases of the materials handling stream, which is attributed to the inter-particle and boundary cohesion and adhesion forces. These characteristics can be computationally expensive to model and with the development of discrete element modelling (DEM) and advancement in computational power over the past decade, it is now more feasible to model WSM's into the DEM technique. This paper will compare two different contact models that can represent the characteristics of a WSM. The first being a simplified Johnson-Kendall-Roberts (JKR) contact model which is an expanded form of the classic Hertz contact model. This model includes the tensile forces which are in the contact zone between two bodies when they are separated, which the Hertz model failed to capture [6]. The second model is that of a liquid bridging contact, which accounts for the capillary effects and surface tension that will form between two bodies such as that of a WSM. These two models were then simulated using LIGGHTS [8] as the software platform for a DEM technique simulation. Finally, qualitative experimental verification was undertaken to assess the applicability of the proposed models, where recommendations were made as to the accuracy of each of the contact models used.

Comparative investigation on modelling wet and sticky material behaviours with a simplified JKR cohesion model and liquid bridging cohesion model in DEM

Kenneth Williams

Papers

Development of new analysis methods for the characterization and classification of wet sticky ores

CFD Simulation of Gas-Solid Flow in Dense Phase Bypass Pneumatic Conveying Using the Euler-Euler Model

Comparative investigation on modelling wet and sticky material behaviours with a simplified JKR cohesion model and liquid bridging cohesion model in DEM

Analysis of impact energy factors in ductile materials using single particle impact tests on gas gun

Electrical capacitance tomography of dense phase pneumatic conveying of flyash powder