Accelerating CFD–DEM simulation of processes with wide particle size distributions--颗粒学报PARTICUOLOGY

Brosh, T., Kalman, H., & Levy, A. (2014). Accelerating CFD–DEM simulation of processes with wide particle size distributions. Particuology, 12, 113–121. https://doi.org/10.1016/j.partic.2013.04.008

Tamir Brosh ^a b *, Haim Kalman ^a, Avi Levy ^a

a Pearlstone Centre for Aeronautical Engineering Studies, Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
b School of Mechanical and Systems Engineering, Stephenson Building, Claremont Road, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom

10.1016/j.partic.2013.04.008

Volume 12, February 2014, Pages 113-121

Received 17 December 2012, Revised 14 March 2013, Accepted 27 April 2013, Available online 17 July 2013.

E-mail: broshta@post.bgu.ac.il; Tamir.brosh@ncl.ac.uk

Highlights

• A detached DEM grid was used to reduce the time needed for CFD–DEM communication.

• The DEM-cells employed a no binary search to decrease the computational effort.

• The DEM-cells were divided into sub-cells to gain further speed up.

• The stiffness of the smallest particles was decreased to allow larger time step.

• Finest particles were eliminated in the simulation.

• DEM comminution simulations can run about 300 times faster.

Abstract

Size-reduction systems have been extensively used in industry for many years. Nevertheless, reliable engineering tools to be used to predict the comminution of particles are scarce. Computational fluid dynamics (CFD)–discrete element model (DEM) numerical simulation may be used to predict such a complex phenomenon and therefore establish a proper design and optimization model for comminution systems. They may also be used to predict attrition in systems where particle attrition is significant. Therefore, empirical comminution functions (which are applicable for any attrition/comminution process), such as: strength distribution, selection, equivalence, breakage, and fatigue, have been integrated into the three-dimensional CFD–DEM simulation tool. The main drawback of such a design tool is the long computational time required owing to the large number of particles and the minute time-step required to maintain a steady solution while simulating the flow of particulate materials with very fine particles.

The present study developed several methods to accelerate CFD–DEM simulations: reducing the number of operations carried out at the single-particle level, constructing a DEM grid detached from the CFD grid enabling a no binary search, generating a sub-grid within the DEM grid to enable a no binary search for fine particles, and increasing the computational time-step and eliminating the finest particles in the simulation while still tracking their contribution to the process.

The total speedup of the simulation process without the elimination of the finest particles was a factor of about 17. The elimination of the finest particles gave additional speedup of a factor of at least 18. Therefore, the simulation of a grinding process can run at least 300 times faster than the conventional method in which a standard no binary search is employed and the smallest particles are tracked.

Graphical abstract

Keywords

CFD; Computational fluid dynamics; DEM; Discrete element model; NBS; No binary search

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