Flow diagram

[2] Flow diagrams are used to structure and order a complex system, or to reveal the underlying structure of the elements and their interaction.

[3] The term flow diagram is used in theory and practice in different meanings.

For example the Information Graphics: A Comprehensive Illustrated Reference by Harris (1999) gives two separate definitions: In the second definition the meaning is limited to the representation of the physical route or flow.

The representation of such a system can be supplemented by one or more flowcharts, which show the sequence of one of the flows in one direction, or any of the control flows to manage the system.

The physical movement of objects from one location to another can also be visualized in a mix of maps and flowchart or sankey diagram, which are called flow maps.

Example of a flow diagram of a nuclear submarine propulsion system.
Sankey Diagram of US Consumer Expenditure in 2012