Manual Group Definition

This chapter shows how to define cell and cellface groups in the parameter file.

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A manual definition of the cell and cellface groups in the parameter file can be carried out in two ways:

  1. Logic definition based on existing groups
  2. Explicit definition by specifying cell/cellface ID's

Groups can be defined using the <ELEMENT_GROUP> and <FACE_GROUP> commands.

Cell Groups

A cell group can be defined by the command <ELEMENT_GROUP>. Three methods are available to define the required group based on existing groups:

  • <MERGE> Merge two or more existing cell groups
  • <INTERSECT> Intersect two or more existing cell groups
  • <XOR> The cells that are contained in exactly one of the given groups

For example, to define a new cell group named MY_CELL_GROUP by merging the two existing cell groups 1_CELLS_A and 2_CELLS_B, the following <ELEMENT_GROUP> command is used: 

<ELEMENT_GROUP>
  <ID_NAME>MY_CELL_GROUP</ID_NAME>
  <MERGE>1_CELLS_A</MERGE>
  <MERGE>2_CELLS_B</MERGE>
</ELEMENT_GROUP>

To define a cell group by explicitly specifying cell IDs (in this case 1 … 10,000), the following <ELEMENT_GROUP> command is used: 

<ELEMENT_GROUP>
  <ID_NAME>MY_CELL_GROUP</ID_NAME>
  <LIST>1-10000:1</LIST>
</ELEMENT_GROUP>

Note: The <MERGE> and <INTERSECT> methods cannot be used together with the cell groups defined by the <LIST> method. The automatically generated cell groups can be used with both, the <MERGE> and the <INTERSECT> method.

Cell Face Groups

A cellface group can be defined by the command <FACE_GROUP>. Three methods are available to define the required group based on existing groups:

  • <MERGE> Merge two or more existing cellface groups
  • <INTERSECT> Intersect two or more existing cellface groups
  • <XOR> The faces that are contained in exactly one of the given groups

For example, to define a new cellface group named MY_CELLFACE_GROUP by merging the two existing cellface groups 1_PART_A and 2_PART_B, the following <FACE_GROUP> command is used: 

<FACE_GROUP>
  <ID_NAME>MY_CELLFACE_GROUP</ID_NAME>
  <MERGE>1_PART_A</MERGE>
  <MERGE>2_PART_B</MERGE>
</FACE_GROUP>

To define a cellface group by explicitly specifying cellface IDs (in this case 1 … 10,000), the following <FACE_GROUP> command is used: 

<FACE_GROUP>
  <ID_NAME>MY_CELLFACE_GROUP</ID_NAME>
  <LIST>1-10000:1</LIST>
</FACE_GROUP>

Note: The <MERGE> and <INTERSECT> methods cannot be used together with the cellface groups defined by the <LIST> method. The automatically generated cellface groups can be used with both, the <MERGE> and the <INTERSECT> method.