zone null command

Syntax

zone null <b > <keep-model> <range>

Sets the null status of all zones in the range. Zones that are null are considered not present for most purposes during calcuations or plotting, but can be un-nulled later. If the boolean value b is not specified it is assumed to be true.

By default, if a zone is made null the constitutive model is removed and all the property values are lost. If the keep-model keyword is specified, then the constitutive model is retained and all properties preserved, in the even the zone is un-nulled with a zone null false command.

If the zone is nulled the stresses in the zone are initialized to zero. Any gridpoints that are made null (meaning no longer connected to anything bug null zones) will have their velocities and displacements initialized to zero.

Note: Unlike previous versions of FLAC3D the null state now applies to all processes - mechanical, thermal, and fluid. To enable a given zone to participate in a the mechanical process but not thermal or fluid use the commands zone fluid cmodel inactive or zone thermal cmodel inactive.