Description

A source is a separate type of entity which can be used to:

  • Control grid density in the isotropic region of unstructured blocks (i.e. it does not affect T-Rex layers).
  • Adapt the interior of structured and voxel blocks.
  • Adapt the boundaries of all block types (i.e. structured, unstructured, and voxel). Note that the bounding domains of voxel blocks are automatically adapted. However, the bounding domains of structured and unstructured blocks need to be assigned to a boundary condition with the Adapt option turned on. For more on boundary adaption see Boundary Conditions for unstructured blocks or Boundary Conditions for structured blocks.
  • Align the isotropic cells of unstructured domains in a general direction defined by a source curve.

The next image illustrates an Examine cut through an unstructured block with a cylindrical source affecting its interior. In this example the source spacings vary from 0.5 at the top, in this image, of the cylinder to 1.0 at the bottom.

Sources can be used to control point density of the isotropic tets in unstructured blocks.
Sources can be used to control point density of the isotropic tets in unstructured blocks.

Several tools in the Create menu can be used to create source entities:

The Sources panel (shown below) is primarily used to adjust Spacing and Decay values for your existing, selected sources. Note that at least one source entity must be selected for the Grid, Sources command to be enabled.

Adjust your source Spacing and Decay using the Sources panel.
Adjust your source Spacing and Decay using the Sources panel.

By default, any source which overlaps a given unstructured block will be set to influence the block's isotropic cell size distribution. This influence is achieved by converting the source into a cloud of points. This point cloud representation will increase in density as spacing values get smaller. This in turn will increase overhead in the block solver and extend the time necessary for the solver to initialize the interior of the block. Therefore it is prudent to start on the conservative side of spacing values initially. The influence of individual sources can be turned on/off in the Grid, Solve, Size Field command tab.

 

Tip: It is prudent to initially use conservative values of source Spacing to decrease the time it takes for a block(s) to initialize.

Newly created sources will have default values for Spacing and Decay set automatically from those found in the Defaults panel. Those values can be updated here or in the Grid, Solve, Size Field command tab.

Spacing and Decay values are applied at the beginning and end locations of each source. These locations are determined by the order in which the ends of the source were originally created. At the top of the Sources panel, there is a table listing current values of spacing and decay for the selected source. If multiple sources are selected, average values will be displayed.

Below the table, the Beginning/Constant Values frame provides entry fields to input new values of Spacing and Decay for the beginning of the currently selected source(s). The Decay parameter has a default value of 0.5 and it varies from 0.0 to 1.0; a value of 0.0 indicates no influence beyond the boundary of the selected source(s) while a value of 1.0 indicates maximum influence. Note that if the selected source has been set to type Constant (see below), it will only be necessary to input the Spacing and Decay values in the Beginning/Constant Values frame for the entire source.

Likewise, additional fields are available in the Ending Values frame to enter values for the end of the currently selected source(s).

Below the input frames you will find the Reverse and Start Interactive Edit commands. The Reverse command allows you to swap beginning and end Spacing and Decay values for the currently selected source(s). The Start Interactive Edit command puts you into a graphical mode for adjusting spacing values at the beginning and end locations. A relatively sized ring (see image below) can be clicked and dragged in the Display window to adjust the corresponding value. The new spacing is dynamically updated in the table for the selected location. When finished adjusting, click Stop Interactive Edit to end the graphical interaction mode.

Start Interactive Mode allows graphical adjustment of the source spacing values.
Start Interactive Mode allows graphical adjustment of the source spacing values.

Finally, at the bottom of the Sources panel you will find the Spacing Type frame, which shows and allows you to select the type of distribution used by the selected source(s).

  • Constant: It changes the source to single valued for spacing and decay throughout the source entity. This will require only a single input for each value, which is the reason the Beginning/Constant Values frame is labeled as such.
  • Parametric (default): Varies the spacing linearly along the source from beginning to end.
  • Axis to Perimeter: Varies the spacing linearly from the axis of the source to its perimeter.
  • Center to Perimeter: Uses a point location and vary the spacing linearly from that point to the entire boundary of the source.
  • Align Only: This option is only available for source curves and it specifies that a given source curve should be used only for domain alignment purposes (i.e. no grid refinement). Refer to the Surface Shape section for more information on domain source alignment.
  • General: Is a special case shown only to indicate what are point cloud sources. Point cloud sources can only be created currently using Glyph.

Demonstration

An Introduction to Sources

Setting Source Attributes