Creating a Hex-dominant Mesh

You can create a hex-dominant mesh for use with fluid flow in the Fluid Scenario Creation app where the increased solution accuracy of hexahedral elements is desirable or where the fluid domain is not part of the model geometry.

Before you begin: A finite element representation must exist. The model must contain a fluid domain definition or contain 3D geometry that represents a fluid volume. If you intend to use digitized data as supports, you must have a license for a Digitized Shape app.
See Also
Hex-dominant Meshing
Finite Element Model Representations
Updating Meshes
  1. From the Mesh section of the action bar, click Hex-Dominant Mesher .
    The Hex-Dominant Mesh dialog box appears.
  2. Optional: Enter a descriptive Name.
  3. Select the solid geometry or fluid domain to be meshed.

    You can also select an orphan mesh or digitized data (from the Digitized Shape apps in the Compass) if model geometry is not available. Orphan mesh selections must be groups of orphan mesh element faces or an orphan mesh part that fully encloses a volume.

    Note: The mesher does not attempt to match orphan mesh faces when creating the hex-dominant mesh. Orphan mesh faces are considered only as a geometric boundary.

  4. Specify the Maximum size, Minimum size, and Minimum angle between faces, or click Initialize from support to set the values based on the size of the selection from Step 2.

    The maximum size is the maximum global element edge size. The minimum size is the smallest element edge size. The angle is the smallest angle between geometric faces that will result in an edge between element faces. All values are approximations.

  5. Optional: Select Add boundary layers to add stacked layers of elements along the region boundaries.

    Boundary layer elements are wedge or hexahedral elements stacked normal to solid walls. The elements are relatively thin in the stacking direction to provide a high mesh density in the direction normal to the fluid flow. This specialized mesh configuration is useful for capturing transition effects such as the significant velocity and temperature gradients that might occur near pipe walls and other structures as viscous and heat transfer effects. The layers decrease in density as they get further from the boundary.

    Note: Boundary layers are not created for solid geometry or for inlets or outlets where no physical boundary exists to impact the flow.

    1. Specify the First layer thickness, which is the layer closest to the boundary.

      The first layer thickness determines the density of the boundary layer.

    2. Specify the Number of layers, or clear this control.

      If this control is inactive, the meshing algorithm determines the number of boundary layers and attempts to create a smooth transition between the first layer thickness and the interior mesh size.

  6. Optional: From the Options section, specify how the hex-dominant mesh should be processed.
    OptionDescription
    Remote host Name of a pre-configured remote host computer to generate the mesh.
    Number of threads Split the mesh computation into multiple pieces.
    Optimize surface treatment Makes another pass over the initial mesh and attempts to regroup and coarsen the highly refined areas that are sometimes found near thin walls. This coarsening reduces the total element count in the mesh while maintaining the resolution of the geometry. This method can increase meshing time for some models, and it is available only for models with a single fluid region.
    Ignore sharp edgeAllows you to ignore features that are either difficult to capture or not important for simulation. This method is useful for conceptual design of products with complex geometry. It favors producing a robust mesh at the expense of sacrificing fidelity to the geometry.
    Trimmed mesh Generates a Cartesian grid mesh with elements trimmed at the boundaries of the geometry. This approach can help you generate the mesh more quickly for some types of simulations, including e-cooling and conjugate heat transfer.

    Notes: Remote hosts must be configured prior to use. For more information, see 3DOrchestrate Installation and Administration Guide: Configuring a Station for Remote Execution of Physics Solvers and Visualization.

  7. Optional: Expand the Local specifications section, and complete the steps to specify the mesh size for faces, for edges, or within a rectangular box.

    To specify a local mesh size for one or more faces or edges:

    1. Click .
      The Local Mesh Size dialog box appears.
    2. Select one or more faces, edges, groups of element faces, or groups of element edges as supports.
    3. Specify the mesh size.
    4. Click OK to save the local mesh specification.
      The local specification is saved in the Mesh Specifications container for the current mesh.

    To specify a local mesh size within a rectangular box:

    1. Click .
      The Local Mesh Size in Cartesian box dialog box appears.
    2. Click to select two corners to define a bounding box, or enter the origin coordinates and size of the box.

      Once you create a bounding box, you can adjust its size and position by dragging the handles on the box displayed in the model.

    3. Specify the mesh size.
    4. Click OK to save the local mesh specification.

    To enable or edit boundary layers locally for one or more faces:

    1. Click .
      The Boundary Layers dialog box appears.
    2. Select one or more faces.
    3. Specify the first layer thickness.
    4. Specify the number of boundary layers.
    5. Click OK.

    To disable a boundary layer mesh locally for one or more faces:

    1. Click .
      The Excluded Boundary Layers dialog box appears.
    2. Select the faces for which you want to disable boundary layers in the mesh.
    3. Click OK.
    The local specification is saved in the Mesh Specifications container for the current mesh.
  8. Click one of the following:
    • OK to save the parameters that you defined, to create the mesh, and to close the dialog box. To generate and visualize the mesh, you must update it.
    • Mesh to save the parameters you defined and to create, update, and generate the mesh.

      The PLM Update progress bar appears. The mesh dialog box remains open to allow further edits.

    • Cancel to cancel the modifications and to close the dialog box.
    If you click OK or Mesh, the mesh specification is created and appears in the tree.