Transition of granular flow patterns in a conical hopper based on superquadric DEM simulations
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ORIGINAL PAPER
Transition of granular flow patterns in a conical hopper based on superquadric DEM simulations Siqiang Wang1 · Ying Yan2 · Shunying Ji1 Received: 18 February 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Granular flow exists widely in nature or industrial production, and particle shape is a crucial factor affecting the flow characteristics of granular materials. In this study, spherical and cylindrical particles are constructed by superquadric equations, and the discharging processes of granular materials in the conical silo are simulated by the discrete element method. Subsequently, the effects of blockiness, aspect ratio and hopper angle on the flow characteristics are investigated. The results show that the discharge rates of cylindrical particles increase and flow fluctuation decreases as the blockiness parameters and aspect ratios decrease or the hopper angles increase. Compared with spherical particles, cylindrical particles are more likely to cause interlocking and hinder sliding or rotation between particles, which results in intermittent granular flow. Furthermore, the flow pattern transition is dominated by the particle shape and hopper angle. The critical height between the mass and funnel flows decreases as the blockiness parameter decreases or the aspect ratio and hopper angle increase and reaches a steady state. However, the effect of particle shape on the flow pattern transition becomes negligible for a larger hopper angle. When the hopper angle is larger than 60°, the granular system basically has a uniform vertical velocity and all particles are in the mass flow. On the microscopic scale, cylindrical particles have a larger average coordination number and greater possibility of strong contact force than spherical particles, which may further cause the flow pattern transition of granular materials on the macroscopic scale. Keywords Discrete element method · Superquadric equation · Particle shape · Granular materials · Flow characteristic
1 Introduction Granular flow exists widely in nature and industrial production, and the discrete element method (DEM) is one of the main tools to study the flow characteristics of granular materials [1–3]. Originally, two-dimensional disc-shaped elements and three-dimensional spherical elements were used to represent the particle shapes because they had simple operations and high efficiency [4, 5]. The granular materials This article is part of the Topical Collection: Flow regimes and phase transitions in granular matter: multiscale modeling from micromechanics to continuum. * Shunying Ji [email protected] 1
State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116023, China
School of Civil Engineering, Dalian Jiaotong University, Dalian 116028, China
2
exhibited mechanical properties similar to solids or liquids under external fields, and underwent solid–liquid transitions under certain conditions [6]. Granular materials typically exhibited anisotropy,
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