Operate on zones. Commands listed here:

Please see the Formulation of a 3D Explicit Finite Volume Model section for a detailed description of FLAC3D zones and their implementation and structure.

Zone elements are connected through gridpoints.

Zones can interact across surfaces with the interface logic using interface nodes and elements.

Zone faces can be used to track and name zone surfaces. It is important to note that there is no actual separate zone face data structure. Zone faces are simply associations made with the boundaries of individual zones. As such zone faces do not have a unique id number, but are instead identified by either a zone ID number and side number pair, or by a list of gridpoint ID numbers.