System Dynamics (SD) is a widely-used graphical notation for representing continuous systems. A System Dynamics diagram typically contains four main types of element: compartments, flows, variables and influences. Compartments represent storages of material, and the flows represent movement of the material into, out of and between compartments. Simile was designed as a “System Dynamics *plus* objects” language, so naturally it is straightforward to represent standard System Dynamics models in Simile.

Some other visual System Dynamics modelling packages, such as Stella, introduce new symbols which extend the System Dynamics language (such as “oven” and “boxcar”). Simile does not have these, but their behaviour can be reproduced using Simile’s core set of model-building elements.