Defining an Arbitrary Section

The arbitrary section is an implicit part that samples one or more input parts or regions. The geometry of an arbitrary section can be created from either a CAD part surface (Root description only) or directly from a STL file. Arbitrary sections should be used when a nonplanar sampling surface is desired.

This representation of the input geometry is mesh-resolution-dependent. A lower polygon count in an arbitrary section results in a faster intersection computation between the section and the sampled region.

To create an arbitrary section:

  1. Follow the general procedure outlined in the section, Defining Derived Parts General Workflow. Choose the menu option, New Part > Section > Arbitrary...
    If the conditions for activating the in-place dialog are not met, the Select Input Surfaces dialog appears.

To define the limits of the arbitrary section, get shape data from part surfaces or an external file:
  1. Specify the part surfaces or import an STL file using one of the following methods:
    • To import an STL file, activate File in either the Select Input Surfaces dialog, or in the Surface Input Options group box in the in-place dialog, then click Browse... and use the Open dialog to select the .stl file to import.

      This action adds the data from the specified file. During the import, Simcenter STAR-CCM+ retriangulates the surface to reduce the number of triangles. The resulting coarser resolution can reduce processing time significantly. However, this retriangulation can also cause problems for surfaces that have curves or other complex characteristics. To disable this feature and retain the resolution of the input file, clear the Decimate input checkbox in the dialog (which is activated by default). Since the surface decimation algorithm is based on the local curvature, planar sections of the surface will not be retriangulated.

    • To use part surfaces, activate Part Surfaces in either the Select Input Surfaces dialog, or in the Surface Input Options group box in the in-place dialog, then click Select... and use the Select Objects dialog to specify the part surfaces.

      This action adds the data from the specified part surfaces. For parts that have multiple descriptions, Simcenter STAR-CCM+ chooses surfaces that belong in the Root description only.

  2. Specify the input parts and display option as described in the section, Defining Derived Parts General Workflow.
    For more information on the available properties, see Implicit Section Properties.