zone face group command


zone face group s keyword ... <range>

Primary keywords:

internal    remove    slot    surface


  • The following nomenclature / equivalence between FLAC3D and FLAC2D is used:
    • Zone faces = zone surface faces in 3D or zone edges (lines connecting gridpoints) in 2D

    • There is no 2D equivalence for 3D zone edges

Adds a group name s to zone faces included in the optional range. Use of the group logic is described in Groups. This command may take the form zone face group "slotname = groupname" — quotation marks required, spaces at equals sign ignored — where slotname is the slot assignment and groupname is the group name.

A zone face may belong to many groups, up to a maximum of 128. The group range element can be used to select objects by group name.

Both the group and the slot can be encoded into the single string s. To do this use the composition ‘slotname=groupname’, where the name to the left of the equals sign will be the slot, and the name to the right will be the group.

Note that by default only surface faces are modified. To select all faces use the internal keyword described below.

The following optional keywords are available:


If specified, then the range looks at internal faces as well as surface faces.


The group is removed from the zone face if present. If the slot keyword is used, then the group is only removed from that slot if present. Otherwise the group is removed from any slot it is found in.

slot s

The group is assigned to the slot named s. If not supplied, the group is assigned to the default slot, which is the one named default.

surface keyword

If specified, then the range looks only at surface faces.


Zones with a non-null fluid model are scanned to determine the surface faces.


Zones with a non-null mechanical model are scanned to determine the surface faces.


By default, if more than one mechanical, thermal or fluid keyword is given, then the zone needs to have all of those conditions to determine a surface face. In other words, if both mechanical and thermal were given, then if the zone had a non-null mechanical model and a null thermal model it would be considered outside the surface. If the or keyword is given, then it is considered inside the surface if any of those conditions has a non-null model.


Zones with a non-null thermal model are scanned to determine the surface faces. Applies only if internal is not specified.