HydroGeoSphere/Defining a New Zone

In order to define a new zone, elements of the proper type must first be chosen using the instructions given in Section 5.4. For example, 3-D block elements must first be selected before a new porous media or dual zone can be defined, 2-D rectangular faces are selected for fracture or surface zones and 1-D segments are selected for channel zones.

In a problem where there are to be dual, fracture, surface or channel zone types, a new zone must be defined since the default situation after grid generation is that there are no elements of these types. This is not the case for porous media zones, where by default all 3-D elements are in porous media zone 1.

Once elements of the appropriate type have been chosen, the following command groups them into a single zone.

New zone

 * 1) num_zone Zone number.

Chosen elements are assigned a new zone number.

If num_zone is greater than the total number of zones of the current media type, the total number of zones will be incremented and default properties for that media type will be assigned.
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The following set of instructions, inserted in the prefix.grok file would create a new fracture zone:

Assign zone zero
Assign all elements to zone number zero.
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This instruction was added for the case where we are using multiple surfaces to choose elements and assign them unique zone numbers. If we first assign all elements to zone zero, we can then find elements that were not chosen by any surface and are still assigned to zone zero.