A geometric potential-based contact detection algorithm for egg-shaped particles in discrete element modeling

This paper presents the development of an algorithm for the contact detection of egg-shaped particles in discrete element modeling and the study of the behaviors of assemblies of egg-shaped particles at macroscopic and microscopic levels. A cubic function extended from the elliptic equation (quadratic function) was used to describe the particle shape. The mass center is deviated from the origin of the cubic function. Therefore, the effect of particle asymmetry can be investigated systematically using these egg-shaped particles. Contact detection was developed based on the geometric potential method for these egg-shaped particles. The resulted optimization problem was solved by the modified Newton's method. A pre-check step was installed to improve the performance. Several anticipated numerical difficulties were circumvented. Although particle asymmetry can be examined by poly-ellipses (formed by two different semi-ellipses), the contact detection of the newly developed egg-shaped particles was found to be faster than that of two poly-ellipses. The contact detection was implemented into the program ELLIPSE2 resulted in a new program EGG2. The effect of particle asymmetry was shown through the packing properties and mechanical behaviors of assemblies of egg-shaped particles. The result demonstrated that these new particles offer the possibility to study particle shape in a wider range which cannot be accomplished by the particles of quadratic function. (C) 2017 Elsevier B.V. All rights reserved.