zone interface element command


zone interface <s > element keyword <range>

Primary keywords:

delete    extra    group    list    maximum-edge


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

    • There is no 2D equivalence for 3D edges

    • 3D volumes <-> 2D areas

    • Element or node effective surface area in 3D <-> Element or node effective length in 2D.

Manage zone interface elements. If the interface name is not given then the command operates on all interfaces.

If an interface name s is given the command is applied only to elements of that interface, otherwise the command is applied to elements in all interfaces in the optional range.


All interface elements associated with this interface within the selected range are deleted.

extra i a[interfaceelementblock]

sets the extra interface element variable value for array index i. The standard [interfaceelementblock] list is available to modify this value in space.

group s <keyword>

Add group name s to the interface elements in the range. Use of the group logic is described in Groups. This command may take the form zone interface element "slotname = groupname" — quotation marks required, spaces at equals sign ignored — where slotname is the slot assignment and groupname is the group name.

An interface element may belong to many groups in different slots, up to a maximum of 128. The group range element can be used to select objects by group name.

The following optional keywords are available:


Remove s from interface elements. If a slot is not specified, the group name is removed from all slots it is found in.

slot s

Assign the group to the slot named s. The default slot name is Default.

list keyword
extra i

Lists the values of the interface element extra variable for array index i.


Nodes, area (in 3D) or length (in 2D), and normal vector of all elements in the range are displayed.

maximum-edge f

f is the maximum edge length for interface elements in the range. The interface is subdivided until all of these elements have an edge length smaller than the assigned value. By default, two triangular elements are created for each quadrilateral zone face in FLAC3D. In FLAC2D, a single line element is created for each zone face.

zone interface element Keyword Block

The following keywords may be used to modify a supplied value. If the description of the modifier keyword mentions what type of value it may be applied to (e.g. scalar value, vector value, etc.), be sure there is a match between the modifier and the main keyword value. The commands main keywords are: extra.


Add the specified value to the existing value.

gradient v <origin v >

Apply a gradient to the scalar-value provided.


Multiply the existing value by the specified value.

vary v

Apply a linear variation to the scalar-value provided.