Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

Contact detection between axially asymmetric ellipsoids in discrete element modeling

S.M. Johnsona,*, J.R. Williamsa, B.K. Cookb
aMassachusetts Institute of Technology, Department of Civil and Environmental Engineering, Cambridge, MA 02139, USA bSandia National Laboratories, Albuquerque, NM 87185, USA

  Full Text
Particulate flow and particulate processing have received renewed interest as the driving needs of industry in understanding powder and particulate systems (e.g. in the manufacture of pharmaceuticals and the deposition of thin powder films) has met the academic development of tools, such as discrete element modeling (DEM) codes, to investigate such systems at a granular scale. The practical limit for the number of particles that can be simulated by the discrete element method depends critically on the particle shape, the data structures, and the algorithms used for contact and force generation. Simple shapes, such as spheres, though optimal in the above aspects, are not always able to reproduce phenomena of interest, and a non-spherical shape needs to be included. The focus of this paper is on representing a particle's geometry as a general ellipsoid in a computationally efficient manner via a new contact resolution algorithm. The algorithm presented here takes advantage of the properties of the normal field of the ellipsoidal geometry in combination with an efficient iterative vector-based search algorithm. Special attention is given to the software implementation of the algorithm, and a discussion of the computational efficiency of the algorithm is also provided.

Keywords:  Discrete element modeling; DEM; Ellipsoids; Computational geometry

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