Commun. Comput. Phys., 10 (2011), pp. 1027-1043.


A Hybrid Algorithm of Event-Driven and Time-Driven Methods for Simulations of Granular Flows

Jun Huang 1*, Ole Jorgen Nydal 1

1 Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway.

Received 16 June 2010; Accepted (in revised version) 21 December 2010
Available online 24 June 2011
doi:10.4208/cicp.160610.211210a

Abstract

The classical discrete element approach (DEM) based on Newtonian dynamics can be divided into two major groups, event-driven methods (EDM) and time-driven methods (TDM). Generally speaking, TDM simulations are suited for cases with high volume fractions where there are collisions between multiple objects. EDM simulations are suited for cases with low volume fractions from the viewpoint of CPU time. A method combining EDM and TDM called Hybrid Algorithm of event-driven and time-driven methods (HAET) is presented in this paper. The HAET method employs TDM for the areas with high volume fractions and EDM for the remaining areas with low volume fractions. It can decrease the CPU time for simulating granular flows with strongly non-uniform volume fractions. In addition, a modified EDM algorithm using a constant time as the lower time step limit is presented. Finally, an example is presented to demonstrate the hybrid algorithm.

AMS subject classifications: 70F05, 65K05, 74S30, 70F10

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Key words: Time-driven method (TDM), event-driven method (EDM), Hybrid algorithm of event-driven and time-driven methods (HAET), granular flow.

*Corresponding author.
Email: jun.huang@ntnu.no (J. Huang), ole.j.nydal@ntnu.no (O. J. Nydal)
 

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