zone create2d command

Syntax

zone create2d keyword

Primary keywords:

annular-sector    quadrilateral    sector    sector-quad    triangle    tunnel-quad    uniform-triangle

Create 2D zones for FLAC2D.

Note

This command creates 2D zones. To create 3D zones for FLAC3D, see the zone create command.

For convenience, the keywords shown here for the zone create2d may be used with the FLAC3D command zone create as well. The latter command passes through these keywords to the zone create2D command.

The zone create2d command creates 2D zone-filled primitive shapes ( quad, triangle, etc.) with a predefined grid pattern.

See Primitive-Based Grids for further discussion and examples of the process of creating a mesh using primitive shapes.

To create zones interactively in the user interface, see the c Sketch tool in the user interface.

FLAC2D may also read in externally generated grids in several formats, see the zone import command.

See Primitive-Based Grids for further discussion and examples of the process of creating a mesh using primitive shapes.

Note

Thumbnails of primitives are links (may be clicked) to enlargements that indicate the shapes’ reference points.

After each shape keyword is a block of modifiers that control its position, shape, and zone distribution. These are marked [zonecreateblock] in the commands, with definitions found in the “Keyword Block” section at the end of this topic.

annular-sector [zonecreateblock]

Create a 2D annular sector:

5 reference points, 3 size entries, 2 dimension entries, fill-able.

quadrilateral [zonecreateblock]

Create a 2D quadrilateral-shaped mesh:

4 reference points, 2 size entries, 0 dimension entries, not fill-able.

sector [zonecreateblock]

Create a 2D sector-shaped mesh:

3 reference points, 2 size entries, 0 dimension entries, not fill-able.

sector-quad [zonecreateblock]

Create a quadrilateral shape with removed sector:

6 reference points, 3 size entries, 2 dimension entries, fill-able.

triangle [zonecreateblock]

Create a triangle-shaped mesh:

3 reference points, 2 size entries, 0 dimension entries, not fill-able.

tunnel-quad [zonecreateblock]

Create a quadrilateral mesh with removed smaller quad:

7 reference points, 3 size entries, 2 dimension entries, fill-able.

uniform-triangle [zonecreateblock]

Create a uniform triangle-shaped mesh:

3 reference points, 2 size entries, 0 dimension entries, not fill-able.

Table 8: Summary of 2D Mesh Shape Properties

Name/Keyword	Reference Points	Size Entries	Dimension Entries	Fill
annular-sector	5	3	2	yes
quadrilateral	4	2	0	no
sector	3	2	0	no
sector-quad	6	3	2	yes
triangle	3	2	0	no
tunnel-quad	7	3	2	yes
uniform-triangle	3	2	0	no

zone create2d Keyword Block

The characteristics of the created shape (e.g., global coordinate positions, number of zones) are defined by specifying the keywords given below, after the shape keyword. The numerical entries associated with each shape are summarized in the table above and illustrated in the figures (click any thumbnail image above for a reference enlargement). The shape keywords of zone.create shown above will accept the keywords listed in the block below, except where noted otherwise in the descriptions. The major keywords are: annular-sector, quadrilateral, sector, sector-quad, triangle, tunnel-quad and uniform-triangle.

dimension f ...

Specify the dimensions of interior regions for some shapes. These are used if the control point is not specifically given. Two dimension entries may be required for a shape (f1, f2). Refer to the figures above for entries and dimensions. If dimension is not given the entries are calculated as 20% of the lengths between reference points.

edge f

Specify an edge length for the sides of the mesh. If point 1 and point 2 are not specified, then the magnitude of the distance from point 0 will be defined by edge. By default the edge length is the number of zones specified in that direction.

fill b <group s1 <slot s2 >>

If specified, the interior region for some shapes (see Summary of 2D Mesh Shape Properties above) will be filled with zones. If not specified, the interior region will not contain zones. If the optional group keyword is given with a valid name, the name s1 is assigned to the filled zones.

group s1 <slot s2 >

Assign a group name s1 to this primitive at creation. By default (when the slot keyword is not supplied), the group is assigned to slot Default. Use of the group logic is described in Groups.

merge b

Gridpoints from newly created zones are merged with existing gridpoints if this keyword is set true. During execution of a zone.create command, a check is made for each gridpoint on new zones boundaries against the boundary gridpoints of zones that already exist. Internal gridpoints are not checked. If two boundary gridpoints fall within a tolerance of 1.e-7 (relative to the magnitude of the gridpoints’ position vector) of each other, they are assumed to be the same point, and existing gridpoint is used instead of creating new ones for all subsequent calculations. If merge is set false, two gridpoints are not merged into one.

point i keyword

The keywords point 0, point 1, point 2 … point 7 specify the reference (corner) points of shapes. By default, point 0 is located at (x = 0, y = 0). By default, point 1, point 2 are set to the orthogonal distances in the \(x\)-, \(y\)-directions, with a magnitude equal to the number of zones in that direction.

Up to 7 points may be required for a shape. The number required is shown in Summary of 2D Mesh Shape Properties above. The locations of these points are illustrated in the reference images (click on any thumbnail above to access).

The following options are available to define the location of any given point

v <add>

The position is given as a vector v. If the optional keyword add is used, the value of v will be added to the position of point 0.

gridpoint s

The position of the gridpoint with name s is used. See the zone gridpoint create command. This allows to user to create named reference points in space ahead of time, and refer to them when creating primitives.

ratio f1 <f2... >

This specifies a ratio that is used to space zones with an increasing or decreasing geometric ratio. This ratio is defined as creating a zone size distribution such that each zone along the edge is f times the previous. Up to three ratio entries (f3) may be needed for some shapes. For each shape, the entries and their associated zone directions are shown in the reference images (click any thumbnail above). If ratio is not given, all entries default to 1.0.

size i1 <i2 ... >

This specifies the number of zones for each shape. Up to three (i3) may be needed for some shapes. The number required is listed in Summary of 2D Mesh Shape Properties above. The entries and their corresponding directions for each shape are shown in the reference images (click any thumbnail above). If not specified, size values default to 10.

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