# zone separate command

Syntax

zone separate keyword

Primary keywords:

separates internal faces, making a new internal surface. Gridpoints are duplicated.

New gridpoints get copies of all group and extra variable assignments belonging to the original face and gridpoint.

There are two methods to separate available:

by-face <range>

Selects internal faces in the range, and separates the gridpoints on either side to make it a new internal surface. New faces get a copy of the original face group assignments.

One (consistent) side of the newly created faces will have a new group assignment made, to make it easier to distinguish one side from the other after creation (since they will be in the same location in space). By default, the new side will be assigned the group NewSideX in slot Separate, where X is a number starting at 1 and incrementing with each zone separate command. The new-side keyword can be used to specify which side is assigned and the group and slot name used.

Note that this command uses a different algorithm than in past versions of FLAC3D, and should work correctly on zone regions that are not perfectly topologically connected, such as commonly result from a zone densify command.

The most recent separation algorithm will leave internal bounaries attached (constistent with an internal fault) and will create more than one new grid point if a region is created with multiple separations (If T-shaped intersecting fault is created, for example).

clear-attach

By default, an error occurs if any gridpoint that has an attach condition associated with it is found among those to be separated. However, if the clear-attach keyword is supplied, then the separation of gridpoints will occur regardless. In addition, FLAC3D will remove any attach conditions connected to gridpoints affected.

new-side keyword
origin v

Specify a location in space used to determine which side is assigned to the new group. If the vector from the origin to the face centroid is in the opposite direction then the group name is assigned. This check is made to the first valid face encountered, and the side is kept consistent from then on. By default, the origin is (0,0,0).

group s <slot s >

Newly created faces will be assigned the group name name in the specified slot. The default slot, which is used if slot s is not supplied, is named Default. FLAC3D determines which face will be new and which one will be old by using the origin keyword. Use of the group logic is described in Groups.

by-zone keyword ...

This version separates zone regions. All grid points connected to zones in range-1 that are also connected to zones in range-2 will be assigned new grid points that are only connected to the zones in range-1.

This can be used to cleanly and completely separate two regions of zones. Note that if this is used to create an internal fault, then the boundaries of the fault will be separated (unlike the by-face keyword above) and the surface will effectly have one face more of separation around the boundary.

While both range-1 abd range-2 are optional, if range-1 is not specified then no separation will occur, since there will be no zones to separate from. If range-2 is not specified then all zones in range-1 will be separated from all other zones in the model – along the entire boundary of the set of zones in range-1.

clear-attach

By default, an error occurs if any gridpoint that has an attach condition associated with it is found among those to be separated. However, if the clear-attach keyword is supplied, then the separation of gridpoints will occur regardless. In addition, FLAC3D will remove any attach conditions connected to gridpoints affected.

range-1 <keyword ...>

Specifies the range used to select zones that will be separated. Any grid points connected to zones in this range that are also connected to zones in range-2 will be separated.

range-2 <keyword ...>

Specifies the zones that will trigger a separation. If left as the default value (all zones included) then the entire boundary of the set of zones in range-1 will be separated.