If an apple is thrown from a rooftop, it falls to the ground. When a baseball player hits a baseball with a bat, the ball is pushed into the field. Objects in a discrete element model behave very similar to the apple and baseball, or any other object on earth.

The discrete element method involves a particle-based system where each particle is subjected to gravity and obeys Newton’s three laws of motion. An example of a DEM simulation is shown to the left from a paper by Morgan and McGovern (2005). Values are assigned to specific properties of the system particles – particle size or density – and inter-particle contacts, like surface roughness or friction. Cohesion, or the sticking together of particles, can also be simulated using bonds assigned between particles that break when subjected to a maximum force (push or pull). If a system has no cohesion, similar to dry sand, there are no bonds assigned between particles. Overall, the system properties will determine how the system will behave mechanically.

This method is very useful for simulating natural systems because it can produce geological behavior. It can also be applied to systems at any scale, but my study uses DEMs for large scale volcanic flanks.