HydroGeoSphere/Inactive Elements

These instructions can be used to discretize irregular boundaries with block elements by deactivating portions of the grid, where all elements become inactive for both the flow and transport simulation. Elemental assembly is skipped and all nodes that only belong to the inactive element, and are not at all connected to active elements, are assigned default values of head and concentration equal to -9999.0. This option is similar to what is done in MODFLOW to specify inactive cells.

The elements becomes inactive

All chosen elements will become inactive.

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Make zone inactive

All elements in the current set of chosen zones will become inactive.

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For a 2-D slice made of 4-node rectangular elements, the following instruction can be used to make elements inactive:

Make element inactive using shapefile

1. arcview_prefix Prefix of the ARCVIEW shape file.
2. unproject_file If .TRUE, this logical switch causes grok to read grid unprojection data as described in Section 5.3.10 and to apply it to the data read from the ARCVIEW shapefile.
3. project_file If .TRUE, this logical switch causes grok to read grid projection data as described in Section 5.3.10 and to apply it to the data read from the ARCVIEW shapefile.
4. outside If .TRUE, elements located outside the area defined in the ARCVIEW shapefile will become inactive. If .FALSE, elements located inside the area will become inactive.

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Write inactive elements to file

1. inactive_file Name of the file to which the inactive element information will be written.

Setting up inactive elements with the Make element inactive using shapefile instruction can be time consuming in grok and this step does not need to be repeated as long as the grid structure remains the same. This instruction is intended to be used in conjunction with the following instruction.

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Read inactive elements from file

1. inactive_file Name of the file from which the inactive element information will be read.

The results of successive calls to this instruction are cumulative, if different sets of inactive elements are read.

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