Validation Tests for Discrete Element Codes Using Single-Contact Systems

Abstract

In recent years, the discrete element method (DEM) has become widely used to solve a number of geological and geophysical problems. The basic idea of this method is to consider rock-soil bodies, in their discontinuous nature, as a set of discrete elements. It is generally recognized that this type of complex model must be validated through comparison with experimental results. Many researchers have addressed this in earlier publications. However, one important aspect has been given little attention, namely, testing the code to ensure that the computer program executes the model specification correctly. This paper describes in detail a DEM program for cohesionless particle vibration and shows four simple simulations used to verify the code. The results of these simulations are compared with PFC (Particle Flow Code 2D) and analytical solutions that are mathematically correct, showing that they have a good consistency. It is concluded that mathematical tests in artificial situations can uncover bugs in programs that appear to be running correctly, even if the programs simulate real experiments reasonably well. The simulation of relative error between numerical solutions and analytical solutions increases as artificial viscosity is introduced. These tests are published with the aim of helping others validate their programs (such as PFC) in similar applications.