The Farfield type is designed to encapsulate existing topology and extend it to a far boundary as part of a new field volume block. As such, the
domains selected will be used as part of the bounding topology of these blocks. A good example of use would be an external flow topology created, for
instance, on a symmetric air vehicle, where those domains on the vehicle up to the symmetry plane already exist. The Farfield type will use those
domains while creating a rectangular far boundary and a linked symmetry domain to produce a new block. Additionally, since automated block creation of this
nature is only practical for unstructured topology, T-Rex tools are provided only for this Build Blocks type for easy setup up front for the T-Rex
tools. Keep in mind the resulting block will still need to be initialized. See
the Solve command for unstructured blocks for more information. Finally, domains
selected for creation of this block type will automatically be used as Size
Field influencers for the new block in the Solve command.
Use the Build Blocks command to create block topology quickly based on existing grid entities.
In the Shape frame (shown below), you can set up symmetry plane definition for the new block as well as its extents. By default for Symmetry
Planes the Automatic toggle is checked meaning the command will try to automatically determine a single or two planes of symmetry
automatically from the selected topology. If for some reason a symmetry plane is not detected automatically you can use the first and second pull-down lists
to select manually. Using one of the two pull-down lists will uncheck the Automatic toggle automatically. You can recheck this toggle to have the
panel restore the automatically detected symmetry plane(s).
In the Margins frame you will find fields to set the extents of the new block in X, Y, and Z coordinates. The Uniform text field allows you
to enter a single number which will be used in all three coordinate directions. This value will automatically populate the individual coordinate directions
just below. Or those fields can be used to enter unique values for each coordinate minimum and maximum.
Use the Shape frame to specify the extents of the new block.
The Spacing Controls frame shown below provides controls to specify how the Boundary Spacing is determined, a Decay value, and
a Background Spacing. Two choices are available for Boundary Spacing: Variable From Size Field and Constant From Size
Field. Variable From Size Field uses the influence of the selected domains, any overlapping sources, the background spacing and
the Decay to set boundary cell sizes locally.
Use the Spacing frame to specify the cell sizing of the new block.
Constant From Size Field will use the Minimum, Average, or Maximum spacing from the selected domains. Once
this Boundary Spacing option has been selected, Size Field Spacing is added to the command frame (shown below) with these three
choices, Minimum being the default.
Constant From Size Field adds the Size Field Spacing choices of Minimum, Average or Maximum to the frame.
Decay defaults to whatever value is specified in the Defaults panel, where
0.5 is the default. Uncheck Use Default to enter a new value. Background Spacing is determined automatically from the selected domains cell
sizes, Decay and Margins of the block. Uncheck Use Default to enter a new value in the text field.
Using the options in the T-Rex frame you can pre-populate attributes and BCs for T-Rex
in the unstructured solver. This includes the number of Layers, Max. and Full, as well as the Growth Rate for advancing
layers. At bottom of this frame you can select the Wall BC to be used for the domains you selected initially to create the block. If there is not an
existing wall BC, click New to create a new BC.
Use the T-Rex frame to specify T-Rex attributes for the new block.
Finally, you can click Update Grid Entities at the bottom of the panel to preview the bounding domains of the pending new block. However, once
saved, the new block will still need to be intialized via the Solve command for
unstructured blocks. If desired, tools in the collapsed Selection frame will provide a selection mode to reselect the domains to be used by the new
block. This would be equivalent to clicking Cancel to exit the command, changing your selection, and entering Build Blocks anew.
Use the Update Grid Entities command to preview the pending block boundaries.
When the new block is complete, click OK to save it and close the panel, click Cancel to discard it and close the panel, or
click Apply to save it and continue on to creating another block.