Description

The T-Rex tab allows you to generate anisotropic layers from the boundaries of unstructured domains. Options are available to chose the type of cells contained in those layers: triangles or a combination of triangles and quadrilaterals.

 

Tip: T-Rex domains can be great for unstructured domains on geometries with high curvature, such as the leading edge of a wing or other airfoil shape.

2D T-Rex Tab
Use the settings on the T-Rex tab of the unstructured domain solver to generate anisotropic triangles.

At the top of the T-Rex tab, a table provides information regarding connectors assigned to a Match T-Rex boundary condition (refer to the Boundary Conditions section for more information) that are used by structured domains. Since the Push Attributes feature (described below) will not affect these connectors in order to avoid unwanted modifications to the structured domains using them, the information displayed on the table is intended to help you determine the appropriate settings for the T-Rex algorithm.

The top of the table shows the total number match connectors being used by structured domains. The table also shows the calculated Layer Count, the calculated Growth Rate, and the Initial Spacing for such connectors. Since multiple match connectors used by structured domains may exist, minimum, average, and maximum values are provided for each measure.

Layers

In the Layers frame you will find the basic settings for generating anisotropic triangle layers in an unstructured domain. These settings apply specifically to those connectors that have been assigned to a T-Rex Wall boundary condition in the Boundary Conditions tab (refer to the Boundary Conditions section for more information).

Use Max. Layers to set the total number of anisotropic triangle layers you wish to generate. This is a target number only. Various physical constraints and quality controls may prevent this target from being achieved. A value of 0 input for Max. Layers turns off the T-Rex anisotropic meshing.

Use Full Layers to set a target for the number of layers you wish to generate without any changes in the deforming front. In other words, the number of target layers to generate prior to any refinement or decimation of the front. This parameter also controls whether the T-Rex solver applies multiple normals (Full Layers = 0) or not (Full Layers > 0).

 

Tip: Always set Full Layers to 0 (zero) when applying T-Rex layers to baffles. This allows the solver to apply multiple normals along the sharp edges of a baffle which otherwise would not be applied, resulting in fewer layers on the baffle and significant scalloping of the layers that are completed. See the image below for an example.

AltText
Use the Full Layers parameter to control whether the T-Rex solver applies multiple normals (Full Layers = 0) or not (Full Layers > 0).

Growth Rate specifies the rate you wish to grow each anisotropic triangle layer as layers deform from the boundary. Uncheck the Use Default toggle to override this setting's default value of 1.2 with your own rate value.

Push Attributes automatically propagates the domain T-Rex attributes to connectors assigned to a T-Rex Match boundary condition (refer to the Boundary Conditions section for more information). Specifically, the initial spacing, the number of layers, and distribution of points on the interior of the T-Rex domain will automatically be matched on these connectors. This option provides a great time savings by avoiding the need for manual matching of T-Rex domains and their perimeter connectors.

Cell Types

The Cell Types frame provides two options to specify the type of cells to be generated by the T-Rex algorithm (i.e. the type of cells in the anisotropic region of the volume grid): Triangles and Triangles and Quads. Use Triangles or Triangles and Quads to create anisotropic layers containing only triangular or a combination of triangular and quadrilateral cells respectively.

Advanced

The Isotropic Height option available in the Advanced frame specifies a scaling factor used to scale the normal isotropic cell height of a vertex. This will allow the T-Rex algorithm to grow anisotropic cells pass the isotropic state (factor larger than one) or to stop the growth of anisotropic cells before they reach the isotropic state (factor smaller than one).

Smoothing

The Smoothing frame provides input fields for Smooth and Relax controlling local cell height Laplacian smoothing. Smooth is the number of smoothing iterations to be applied. Relax is a factor controlling the influence of the smoothing, varying between 0 and 1. For both parameters, uncheck Use Default to override the default values.

 

Tip: The more quality measures you enforce on your T-Rex layers the less layers you will likely get as more stringent criteria force the checking to stop advancing the front in more areas. Therefore, try to be as relaxed as possible on quality criteria settings.

Demonstration

T-Rex Layers

Resolving High Curvature with 2D T-Rex

T-Rex Smoothing Parameters