Discrete element simulation of cylindrical particles using super-ellipsoids--颗粒学报PARTICUOLOGY

Zhao, Y., Xu, L., Umbanhowar, P. B., & Lueptow, R. M. (2019). Discrete element simulation of cylindrical particles using super-ellipsoids. Particuology, 46, 55-66. https://doi.org/10.1016/j.partic.2018.04.007

Discrete element simulation of cylindrical particles using super-ellipsoids

Yongzhi Zhao ^{a b *}, Lei Xu ^a, Paul B. Umbanhowar ^b, Richard M. Lueptow ^{b c d *}

a Institute of Process Equipment, College of Energy Engineering, Zhejiang University, Hangzhou 310027, China
b Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, USA
c Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA
d The Northwestern Institute on Complex Systems (NICO), Northwestern University, Evanston, Illinois 60208, USA

10.1016/j.partic.2018.04.007

Volume 46, October 2019, Pages 55-66

Received 11 March 2017, Revised 26 March 2018, Accepted 4 April 2018, Available online 8 June 2019, Version of Record 8 August 2019.

E-mail: yzzhao@zju.edu.cn; rlueptow@northwestern.edu

Highlights

• The DEM based on super-ellipsoids was used to simulate cylindrical particle flow.

• An oriented bounding box algorithm (OBBA) was developed to accelerate contact detection.

• The OBBA is more suitable for rod-like particles with a large aspect ratio.

• Particle shape affects the super-ellipsoid DEM simulation speed significantly.

Abstract

A discrete element model based on super-ellipsoids was used to simulate cylindrical particle flow. The model can describe a cylindrical particle accurately provided the shape indices of the super-ellipsoids are set to appropriate values. To achieve more rapid calculations, we implemented an “oriented bounding box algorithm” (OBBA) for the initial contact detection of cylindrical particles. Several types of simulations were performed to validate the super-ellipsoid model and the contact-detection algorithm. First, the effect of shape index of the super-ellipsoids on model accuracy was investigated through three simulations: impact of a cylindrical particle on a flat wall, flow of cylindrical particles in a rotating tumbler, and segregation of cylindrical particles of different length flowing down a bounded heap. The simulation results show that the super-ellipsoids describe cylindrical particles accurately when the shape index that specifies the sharpness of the cylinder edges is sufficiently large. The efficiency of the OBBA is measured by simulations in which a box is filled with cylindrical particles and a tumbler that contains cylindrical particles is rotated. The simulation results show that the OBBA can accelerate the calculations significantly. The effect of particle shape (such as aspect ratio and shape index) on the calculation speed was obtained. The simulation of rod-like particles tended to take more calculation time than that of disk-like particles, and the simulation time increased with an increasing particle-shape index.

Graphical abstract

Keywords

Discrete element method; Super-ellipsoid; Super-quadric; Cylindrical particle; Non-spherical particle; Granular material

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