Computing Axisymmetric Parametric Coordinates

Computing axisymmetric parametric coordinates requires you to identify part surfaces that compose each of the bounding surfaces of the domain—in the case of turbomachinery, all six bounding surfaces. (In this section turbomachinery is discussed as an example due to the frequency of the application.) When the coordinate computation is complete, several field functions are available for you to use in defining isosurface derived parts.

Before you start work with parameterization, import the geometry of your turbomachinery model. Consider the following as you prepare your geometry:
  • If your model has multiple blade rows, there must be interfaces or part contacts between the rows.
  • If not already defined, create a cylindrical coordinate system whose z axis is aligned with the axial direction of the blade rows. See Coordinate Systems.
  • Setting up a parameterization requires selection of parts and part surfaces (or regions and boundaries). If these parts and surfaces are tagged beforehand, you can then use dynamic queries based on these tags when making selections. (See Tagging Simulation Objects and Using Query-Based Selection.)
  1. Right-click the Tools > Parameterizations node and select New > Axisymmetric.
  2. If you prefer, rename the [parameterization] node, which is named by default Axisymmetric, to reflect the particular geometry with which it interacts.
  3. Select the [parameterization] node and set its properties as follows:
    1. Set Cylindrical Coordinate System to the underlying local coordinate system for the geometry.
    2. Set Geometry to contain all the geometry parts or regions for the rows that you wish to include within this parameterization.
      Only surfaces that belong to parts or regions selected here are available for selection in the child nodes.
    In general it is not necessary to modify Computation Mesh Resolution.
  4. To define the bounds of the parameterization in the meridional direction:
    1. Select the Meridional child node and set Min to all surfaces through which flow enters the first blade row.
    2. Set Max to all surfaces through which flow leaves the last blade row (if the parameterization spans multiple rows).
    3. If your parameterization spans multiple blade rows, set Interfaces to the surfaces on each side of the interfaces between successive blade rows.
  5. Set the properties of the Spanwise direction sub-node:
    1. For Min, choose all surfaces that make up the hub.
      Do not select a cooling passage that is typically a part of the geometry for a turbomachine hub. Rather, restrict your surface choices to the actual hub.
    2. For Max, choose all surfaces that make up the shroud.
    NoteIf your model has multiple blade rows, you must specify the hub and shroud surfaces for each row.
  6. Set the properties of the Circumferential (rotation) direction sub-node.

    In the current version of Simcenter STAR-CCM+, geometry of a full turbomachine is not yet supported. Therefore you specify this direction using periodic surfaces.

    If a periodic interface is composed from more than one part surface, be sure to choose the same side of the interface for each component part surface.

When defined correctly, the parameterization registers several field functions that you can use in creating isosurface derived parts on which to render simulation data such as Axial Velocity. To see the list of functions, refer to Parameterization Field Functions.

You can now apply the axisymmetric parameterization in derived parts that you subsequently use in scenes and plots. The transform can be used directly in a scene. See Applying Axisymmetric Parametric Coordinates.

NoteThe parameters are computed for the input regions (geometry parts) selected for the axisymmetric parameterization. If there are boundaries or part surfaces that are part of that region but are not input to the direction parameters (for example the blade) the parameter field functions are still computed on the blade as part of the region.