Application of the discrete element method (DEM) to real scale engineering problems involving three‐dimensional modelling of large, non‐spherical particles must consider the…
Abstract
Application of the discrete element method (DEM) to real scale engineering problems involving three‐dimensional modelling of large, non‐spherical particles must consider the inertia tensor and temporal change in the orientation of the particles when calculating the rotational motion. This factor has commonly been neglected in discrete element modelling although it will significantly influence the dynamic behaviour of non‐spherical particles. In this paper two methods, vector transformation and tensor transformation, for calculation of the rotational motion of particles in response to applied moments are presented. The methods consider the inertia tensor and the local object frame of arbitrary shaped particles and suggest solutions for the non‐linear Euler equations for calculation of their rotational motion. They are discussed with respect to implementation into a discrete element code and assessed in terms of their accuracy and computational efficiency.
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Andrew Phillip Grima and Peter Wilhelm Wypych
The purpose of this paper is to examine several calibration techniques that have been developed to determine the discrete element method (DEM) parameters for slow and rapid…
Abstract
Purpose
The purpose of this paper is to examine several calibration techniques that have been developed to determine the discrete element method (DEM) parameters for slow and rapid unconfined flow of granular conical pile formation. This paper also aims to discuss some of the methods currently employed to scale particle properties to reduce computational resources and time to solve large DEM models.
Design/methodology/approach
DEM models have been calibrated against simple bench‐scale experimental results to examine the validity of selected parameters for the contact, material and mechanical models to simulate the dynamic and static behaviour of cohesionless polyethylene pellets. Methods to determine quantifiable single particle parameters such as static friction and the coefficient of restitution have been highlighted. Numerical and experimental granular pile formation has been investigated using different slumping and pouring techniques to examine the dependency of the type of flow mechanism on the DEM parameters.
Findings
The proposed methods can provide cost effective and simple techniques to determine suitable input parameters for DEM models. Rolling friction and particle shape representation has shown to have a significant influence on the bulk flow characteristics via a sensitivity analysis and needs to be accessed based on the environmental conditions.
Originality/value
This paper describes several effective known and novel methodologies to characterise granular materials that are needed to accurately model granular flow using the DEM to provide valuable quantitative data. For the DEM to be a viable predictive tool in industrial applications which often contain huge quantities of particles with random particle shapes and irregular properties, quick and validated techniques to “tune” DEM models are necessary.
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While there has been extensive commentary and research on issues relating to student academic integrity, the behavior (or misbehavior) of faculty has been less explored. Research…
Abstract
While there has been extensive commentary and research on issues relating to student academic integrity, the behavior (or misbehavior) of faculty has been less explored. Research misconduct and misbehavior is shaped by environmental forces acting at four distinct levels: individual, organizational, educational system, and social (Anderson, 2011; see also Bertram Gallant & Kalichman, 2011). This chapter explores the current climate in higher education whereby academics are under increasing pressure to publish, and how this pressure impacts standards of ethical conduct in academic publishing in the online environment. The chapter argues that to maintain integrity in online publishing environments, there needs to be a multi-stakeholder approach that encompasses each of the environmental levels, from educational policy makers, to senior managers, to teaching academics and advisors, to editors and finally to individual researchers/authors. In addition to recognizing the value of including standard protocols in online journals' instructions to authors, this chapter makes the case for a politicized response to the seemingly limitless pressure on academics to prove their worth by measuring their intellectual outputs.
J.F. Favier, M.H. Abbaspour‐Fard, M. Kremmer and A.O. Raji
A new method of representing non‐spherical, smooth‐surfaced, axi‐symmetrical particles in discrete element (DE) simulation using model particles comprising overlapping spheres of…
Abstract
A new method of representing non‐spherical, smooth‐surfaced, axi‐symmetrical particles in discrete element (DE) simulation using model particles comprising overlapping spheres of arbitrary size whose centres are fixed in position relative to each other along the major axis of symmetry of the particle is presented. Contact detection and calculation of force‐deformation and particle movement is achieved using standard DE techniques modified to integrate the behaviour of each element sphere with that of the multi‐element particle to which it belongs. The method enables the dynamic behaviour of particles of high aspect ratio and irregular curvature (in two dimensions) to be modelled. The use of spheres to represent a particle takes advantage of the computational speed and accuracy of contact detection for spheres, which should make the method comparable in computational efficiency to alternative schemes for representing non‐spherical particles.
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Saeed Hasanpoor, Zahra Mansourpour and Navid Mostoufi
The purpose of this paper is to fundamentally develop a mathematical model for predicting the particle size distribution (PSD) in fluidized beds because their hydrodynamics depend…
Abstract
Purpose
The purpose of this paper is to fundamentally develop a mathematical model for predicting the particle size distribution (PSD) in fluidized beds because their hydrodynamics depend on the PSD and its evolution during operation. To predict the gradual PSD change in a fluidized bed by using the population balance method (PBM), the kinetic parameter for agglomerate formation should be known and this parameter, in this work, is determined by the results of computational fluid dynamic–discrete element method (CFD-DEM) simulation.
Design/methodology/approach
Momentum and energy conservation equations and soft-sphere DEM are used to simulate the agglomeration phenomenon at high temperature in a two-dimensional air-polyethylene fluidized bed in bubbling regime. The Navier–Stokes equations for motion of gas are solved by the SIMPLE algorithm. Newton’s second law of motion is applied to describe the motion of individual particles. Collision between particles is detected by the no-binary search algorithm.
Findings
A correlation is proposed for estimating the kinetic parameter for agglomerate formation based on collision frequency, collision efficiency and inlet gas temperature. Based on the corrected kinetic parameter, the PBM is able to predict the PSD evolution in the fluidized bed in a fairly good agreement with the results of the CFD-DEM.
Research limitations/implications
The results of the agglomeration process cannot be compared quantitatively with experimental results. Because three-dimensional fluidized bed mostly contains millions of particles and simulating them takes a long computing time in DEM. As far as temperature is a dominant parameter in the agglomeration process, effects of inlet gas temperature are examined on the kinetic parameter. On the other hand, wider and deeper insights in which the effect of other parameters, such as velocity and so on will be studied, is one of the goals in the authors’ next works to compensate for the shortcomings in this work.
Originality/value
This study helps to understand the effect of the inlet gas temperature during the agglomeration process on the kinetic parameter and provides fundamental information in dealing with kinetic parameter to attain PSD in fluidized bed by the PBM.
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Xiaoyue Wang, Zhanfu Li, Xin Tong and Xiaole Ge
The purpose of this study is to explore how particle shape influences the screening, including screening efficiency per unit time, and the relationship between vibration…
Abstract
Purpose
The purpose of this study is to explore how particle shape influences the screening, including screening efficiency per unit time, and the relationship between vibration parameters and screening efficiency per unit time in discrete element method (DEM) numerical simulations.
Design/methodology/approach
In this paper, a three-dimensional discrete element model of vibrating screen with composite vibration form of swing and translation was proposed to simulate the screening process. In total, 11 kinds of non-spherical particles whose shapes changed in a continuous regularity gradual process were established using a multi-sphere method. In the DEM simulations, vibration parameters, including vibration frequency, vibration amplitude and stroke angle, and swing parameters, including swing frequency and swing angle, were changed to perform parametric studies.
Findings
It shows that the effect of particle shape on screening efficiency is quantitative actually. However, the trends of different shape particles’ screening efficiency per unit time are mainly consistent.
Originality/value
Some simple particle shapes can be expected to be explored to do screening simulation studies reasonably with modification of the simulation data in DEM numerical simulations. That may improve the computational efficiency of numerical simulations and provide guidance to the study of the screening process.
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E. Tijskens, J. De Baerdemaeker and H. Ramon
Particles in granular matter can have very different and irregular shapes. The computational treatment of nonspherical objects is a major difficulty in the simulation of granular…
Abstract
Particles in granular matter can have very different and irregular shapes. The computational treatment of nonspherical objects is a major difficulty in the simulation of granular flows. In this paper, two basic strategies for contact resolution between objects described by level surfaces are presented and analyzed. They are based on the iterative solution of systems of nonlinear equations. The major difficulties are pinpointed and necessary steps toward a generic algorithm are proposed. A test case of colliding cardioids in two dimensions is used to demonstrate the algorithms and illustrate common pitfalls.
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Beichuan Yan, Richard A. Regueiro and Stein Sture
The purpose of this paper is to develop a discrete element (DE) and multiscale modeling methodology to represent granular media at their particle scale as they interface solid…
Abstract
Purpose
The purpose of this paper is to develop a discrete element (DE) and multiscale modeling methodology to represent granular media at their particle scale as they interface solid deformable bodies, such as soil‐tool, tire, penetrometer, pile, etc., interfaces.
Design/methodology/approach
A three‐dimensional ellipsoidal discrete element method (DEM) is developed to more physically represent particle shape in granular media while retaining the efficiency of smooth contact interface conditions for computation. DE coupling to finite element (FE) facets is presented to demonstrate initially the development of overlapping bridging scale methods for concurrent multiscale modeling of granular media.
Findings
A closed‐form solution of ellipsoidal particle contact resolution and stiffness is presented and demonstrated for two particle, and many particle contact simulations, during gravity deposition, and quasi‐static oedometer, triaxial compression, and pile penetration. The DE‐FE facet coupling demonstrates the potential to alleviate artificial boundary effects in the shear deformation region between DEM granular media and deformable solid bodies.
Research limitations/implications
The research is being extended to couple more robustly the ellipsoidal DEM code and a higher order continuum FE code via overlapping bridging scale methods, in order to remove dependence of penetration/shear resistance on the boundary placement for DE simulation.
Practical implications
When concurrent multiscale computational modeling of interface conditions between deformable solid bodies and granular materials reaches maturity, modelers will be able to simulate the mechanical behavior accounting for physical particle sizes and flow in the interface region, and thus design their tool, tire, penetrometer, or pile accordingly.
Originality/value
A closed‐form solution for ellipsoidal particle contact is demonstrated in this paper, and the ability to couple DE to FE facets.
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The purpose of this paper is to present an educational approach to elevating problem-solving and numeracy competencies of business undergraduates to meet workplace demand. The…
Abstract
Purpose
The purpose of this paper is to present an educational approach to elevating problem-solving and numeracy competencies of business undergraduates to meet workplace demand. The approach is grounded in the theory of constraints following the Decoding the Discipline model. The authors investigated a cognitive bottleneck involving problem modeling and an affective bottleneck concerning low self-efficacy of numeracy and designed specific interventions to address both bottlenecks simultaneously. The authors implemented the proposed approach in an introductory level analytics course in business operations.
Design/methodology/approach
The authors use an empirical study to evaluate the effectiveness of the proposed approach in addressing deficiency in numeracy and problem-solving skills. Cognitive and affective learning interventions were introduced in an undergraduate core course in analytics. The perceived effectiveness of the interventions was evaluated with the use of a survey at the end of the course. To further investigate the effectiveness of the proposed interventions beyond self-reporting, the impact of the interventions on actual learning was evaluated by comparing the exam scores between classes with and without the interventions.
Findings
Students who underwent the interventions successfully overcame both learning bottlenecks and indicated a positive change in attitude toward the analytics discipline as well as achieved higher exam scores in the analytics course.
Research limitations/implications
This study succeeds in strengthening the body of research in teaching and learning. The authors also offer a holistic treatment of cognitive and affective learning bottlenecks, and provide empirical evidence to support the effectiveness of the proposed approach in elevating numeracy and problem-solving competencies of business undergraduates.
Practical implications
The proposed approach is useful for business educators to improve business students’ quantitative modeling skill and attitude. Researchers can also extend the approach to other courses and settings to build up the body of research in learning and skill development. Educational policy makers may consider promoting promising approaches to improve students’ quantitative skill development. They can also set a high standard for higher education institutions to assess students’ numeracy and problem-solving competencies. Employers will find college graduates bring to their initial positions the high levels of numeracy and problem-solving skills demanded for knowledge work to sustain business growth and innovation.
Social implications
As students’ numeracy and problem-solving skills are raised, they will develop an aptitude for quantitative-oriented coursework that equips them with the set of quantitative information-processing skills needed to succeed in the twenty-first century society and global economy.
Originality/value
The proposed approach provides a goal-oriented three-step process to improve learning by overcoming learning bottlenecks as constraints of a learning process. The integral focus on identifying learning bottlenecks, creating learning interventions and assessing learning outcomes in the proposed approach is instrumental in introducing manageable interventions to address challenges in student learning thereby elevating students’ numeracy and problem-solving competencies.
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Jobin Jacob, Arun Antony Chully, Benny J. Godwin and Jossy P. George
The purpose of this paper is to assess green marketing as an influential factor in the purchase of real estate. In this study, the consumer citizenship behaviour of young…
Abstract
Purpose
The purpose of this paper is to assess green marketing as an influential factor in the purchase of real estate. In this study, the consumer citizenship behaviour of young individuals will be studied with an assessment of real estate purchase intention, strategic green marketing orientation (GMO) and tactical GMO.
Design/methodology/approach
The sample frame consists of young consumers from India’s metropolitan cities. The respondents were in the range of 18 to 35 years of age. These cities provide a high standard of living, more career options and better educational opportunities. Five separate sections of a standardised questionnaire were used, and a structural equation model was used to assess a total of 393 valid replies.
Findings
Green marketing impacts the behaviour that influences the desire of young customer to buy green real estate.
Research limitations/implications
As the focus of this study is primarily on major cities, future research may study similar behaviour in non-metropolitan cities. The study can also be conducted among consumers of other age groups.
Originality/value
The originality, to the best of the author’s knowledge, exists in examining how young consumers’ opinions about green marketing impact their intentions to purchase green houses and real estate in India. This study will be accessible to all parties involved in the housing and real estate industries.