Discrete Element Methods (DEM) are a family of numerical modeling techniques designed to solve problems in engineering and applied science that exhibit gross discontinuous behavior. It should be noted that problems dominated by discontinuum behavior can NOT be simulated with conventional continuum based computer modeling methods such as finite element or finite difference procedures. There are a large number of examples, such as geo-engineering problems dominated by discontinuum behavior, including stability of underground mine openings, stability of rock slopes, micro-mechanical behavior of particular media, mineral processing and the flow of bulk solids (as in hoppers, bins, feeders, chutes, screens, crushers, mills, mixers, all types of conveyor systems and many more). In addition, the discontinuum and continuum can be coupled together to create analysis tools that provide us with better understanding of the behavior of material handled and the processing of it.

In simple terms, DEM explicitly models the dynamic behaviors and mechanical interactions of each body or particle in the physical problem throughout a simulation in time, and provides a detailed description of the velocities, positions, and forces acting on each body or particle at a discrete point in time during the analysis. The fundamental unit of a discrete element scheme is the single body or grain. In contrast to the finite element approach, which often assembles a global, functional for the total system, the discrete element method views the individual grain or body as the fundamental unit. Interaction with neighboring grains is achieved by replacing the contact conditions between bodies by external forces. All communication between bodies occurs through boundary forces and not through a global stiffness matrix.

Vitual Prototyping

Computer simulation or virtual prototyping is the discipline of designing a model of an actual or theoretical physical system, executing the model on a digital computer, and analyzing the execution output. Simulation embodies the principle of "learning by doing.''  To learn about the system we must first build a model of some sort and then operate the model. The use of simulation is an activity that is natural as a child who role -plays. Children understand the world around them by simulating (with toys and figurines) most of their interactions with other people, animals and objects. As adults, we lose some of this childlike behavior but recapture it later through computer simulation. To understand reality and all of its complexity, we must build artificial objects and dynamically act out roles with them. Computer simulation is the electronic equivalent of this type of role -playing and it serves to drive synthetic environments and virtual worlds.