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Pre-Processing
Simcenter STAR-CCM+ solves physics problems on a computational mesh. To provide this mesh, you first define geometry using internal or external tools, and then create a mesh pipeline whose operations generate the mesh in repeatable steps.
Modeling Geometry
This part of the User Guide describes how to use 3D-CAD, the parametric solid modeler available within Simcenter STAR-CCM+. It also describes the features and tools available for further preparation of the geometry model and its surfaces.
Understanding Geometry Parts
You can use the geometry parts manager node to control what parts are meshed and included in the simulation downstream.
What Is Metadata?
The metadata specifier can be used to associate a key and value with the part.

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Pre-Processing
Simcenter STAR-CCM+ solves physics problems on a computational mesh. To provide this mesh, you first define geometry using internal or external tools, and then create a mesh pipeline whose operations generate the mesh in repeatable steps.
- 3D-CAD
  3D-CAD is a feature-based parametric modeler within Simcenter STAR-CCM+ that allows you to build geometries from scratch. The geometries that you create with 3D-CAD are stored as 3D-CAD models, which you can then convert to geometry parts for integration with the meshing and simulation process.
- Modeling Geometry
  This part of the User Guide describes how to use 3D-CAD, the parametric solid modeler available within Simcenter STAR-CCM+. It also describes the features and tools available for further preparation of the geometry model and its surfaces.
  - Preparing the Geometry
    In general, a Simcenter STAR-CCM+ analysis requires one or more geometry parts from which you define the spatial construction of the regions. Simcenter STAR-CCM+ allows you to create geometry parts directly using the built-in 3D-CAD modeler, or import geometry from a wide range of source formats.
  - Importing Geometry
    One of the possible starting points for the meshing process is to import surface data.
  - Understanding Geometry Parts
    You can use the geometry parts manager node to control what parts are meshed and included in the simulation downstream.
    - Geometry Parts
      A geometry part is a collection of surfaces and curves that you wish to address as one object. Parts surfaces and curves can be defined by CAD data or discrete (surface mesh) data, depending on the type of geometry part. A single object is referred to as a leaf-level part; a collection of geometry parts is referred to as a composite part. A surface can contain one or more sets of faces and a curve can contain one or more sets of edges.
    - What Is Metadata?
      The metadata specifier can be used to associate a key and value with the part.
      - Metadata on Part Surfaces
        Part surfaces can also have metadata.
    - Creating and Importing Parts
      Geometry parts can be created in the following ways
    - Organizing Assemblies Using Composite Parts
      Composite parts allow other parts to be grouped into assemblies and subassemblies for easier organization.
    - Using Part Contact Data to Create Interfaces
      A geometry part has a Contacts property that provides a list of all other parts with which the part is in contact. This part contact data can be used to generate interfaces for meshing and physics coupling automatically without having to create and assign coincident faces manually.
    - Updating Part Interfaces
      Updating part interfaces between two regions becomes necessary when one or more interfacing parts have been modified or have changed region.
  - Manipulating Parts
    Simcenter STAR-CCM+ allows leaf-level parts to be manipulated in several different ways once they have been imported or created.
  - Part Contacts
    Part contacts define the connection between two part surfaces. The meshers aim to generate a conformal mesh at the contact, which then becomes an interface in the physics region.
  - Repairing CAD Geometry
    The Geometry Repair tool provides diagnostic checks for assessing the validity of geometry and the means to repair the geometry automatically.
  - Displaying the Geometry
- The Surface Repair Tool
  The Surface Repair tool diagnoses errors in, and provides repair tools for, tessellated surfaces and part curves. The same tool allows you to reorganize discretized geometry by searching for face-based features and attributes then assigning the results to new or existing part surfaces or curves.
- Defining the Regions Layout
  An essential part of the process in setting up your simulation is to define the relationship between geometry parts and regions, boundaries, and interfaces.
- Meshing
  A mesh is a discretized representation of a geometric domain. This domain can include real-world geometry, its content, and its surrounding environment.

What Is Metadata?

The metadata specifier can be used to associate a key and value with the part.

A key is typically a property of the part, such as “material”, “color” or “grade”. The value is the respective quantity or identifier, such as “steel”, “blue” or “2”. The value can be either a string (word) or an integer. In order to create a valid metadata input, both a key and a value must be specified. Each geometry part can have one or more metadata that are specified for it.

Metadata must be entered using the format {key:value}. For example:

{material:steel}

If more than one metadata specifier is required for the part or part surface, then a comma can be used to separate them. For example:

{material:steel,color:blue}

The Properties window lets you enter the metadata key and value for the part:

The specifier can be entered directly in the window (within the {} braces) or the button can be pressed to open the property customizer window. The metadata specifier can then be entered. For example:

Clicking OK applies the metadata text and reorganizes it if necessary to conform to the requirements of Simcenter STAR-CCM+. The metadata can be reviewed afterwards in the part Properties window:

Notice that Simcenter STAR-CCM+ automatically adds quotation marks ‘’ to material, steel, and grade, but not to the 2. When quotation marks are not applied, this means that the 2 is an integer value. When quotation marks are applied to the value, for example {‘grade’:’2’}, this means that the 2 is a string. The same holds true for decimal values {‘grade’:2.0} and boolean values {‘conductive’:true}, where the quotation marks around the value are omitted.

You can transfer the metadata available on parts to 3D-CAD using the Edit in 3D-CAD right-click option. In 3D-CAD, you can edit metadata using the 3D-CAD metadata table. For more information, see Metadata in 3D-CAD.

The metadata can also be used as part of a filter or series of filters in order to help identify and select parts at a later stage within Simcenter STAR-CCM+. The metadata specifier has no influence on the simulation and is provided as an organizational feature only.