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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.
Meshing
A mesh is a discretized representation of a geometric domain. This domain can include real-world geometry, its content, and its surrounding environment.
The Meshing Workflow
This section contains the recommended workflow for setting up and generating the volume mesh at the parts level.
Surface Wrapping the Geometry
The Surface Wrapper generates a closed and manifold surface mesh from poor quality or complex CAD geometry.
Creating the Surface Wrap Operation and Selecting the Parts to Wrap
Create a Surface Wrapper operation and select the parts to wrap.

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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.
- 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.
  - Mesh Construction
    Within a bounding volume defined by geometrical surfaces, Simcenter STAR-CCM+ can construct meshes for finite volume and finite element solvers.
  - Meshers in Simcenter STAR-CCM+
    The meshers in Simcenter STAR-CCM+ generate surface and volume meshes for geometry parts that are assigned to regions and make them ready for analysis.
  - Parts-Based Meshing
    Parts-based meshing (PBM) is a meshing strategy in which you create one or more mesh operations that define workflows for preparing, fixing, and processing geometry. A major benefit of PBM is that every mesh operation you create forms part of a linear and repeatable process.
  - The Meshing Workflow
    This section contains the recommended workflow for setting up and generating the volume mesh at the parts level.
    - Preparing Geometry for Meshing
    - Surface Wrapping the Geometry
      The Surface Wrapper generates a closed and manifold surface mesh from poor quality or complex CAD geometry.
      - Creating the Surface Wrap Operation and Selecting the Parts to Wrap
        Create a Surface Wrapper operation and select the parts to wrap.
      - Closing Gaps and Checking for Leaks
        Identify and close any obvious gaps in the geometry. Run the leak detection tool to identify less obvious gaps and holes.
      - Preventing Surface Contact
        Contact prevention ensures that selected close surfaces do not touch each other in the wrapped surface.
      - Setting the Volume of Interest and Wrap Properties
        The volume of interest control determines the volume that the surface wrapper extracts from the input parts. The wrapper properties control the wrap.
      - Generating a Basic Wrap and Checking the Fidelity
        Generate a basic wrap and check the fidelity.
      - Refining the Wrap
        Typically you wrap geometry using coarse settings before refining the wrap. Local wrapping speeds up the re-execution of the surface wrapper after local changes are made to the input geometry or wrapper settings. With this feature, Simcenter STAR-CCM+ only wraps surfaces within a defined location and leaves other surfaces unchanged. Surfaces that are excluded by the partial wrapping option are not wrapped by local wrapping.
      - Assigning Wrapped Parts to Regions
        There are three different procedures to assign wrapped parts to regions, depending on what you want to achieve.
    - Generating the Surface and Volume Mesh
      Meshing parts generates the surface and volume discretization of the imported CAD geometry. The solvers use this discretization to obtain a physical solution.
    - Local Meshing
      Local meshing speeds up the re-execution of mesh generation after changes are made to the geometry or mesh settings (and you already have an initial completed mesh). With this feature, Simcenter STAR-CCM+ remeshes surfaces or volume within a defined location without regenerating a complete mesh.
    - Creating a Parts-Based Mesh with Baffles
    - Creating Shells from Parts
      Simcenter STAR-CCM+ provides support for thin-walled structures that are best represented by a two-dimensional cell layer during simulation. These single-cell layers are known as shells.
    - Anisotropic Meshing for Lifting Surfaces
      Anisotropic meshing allows you to generate a surface mesh that contains stretched quad elements aligned with features (anisotropic faces). By using stretched elements, you can reduce the number of faces in the mesh while retaining geometrical and solution accuracy.
    - Extruding Surfaces from a Parts-Based Volume Mesh
      Use the extruder to extend the existing volume mesh beyond the original dimensions of the starting surface, normal to the existing volume mesh, or in a specified direction.
    - Replacing a Part in a Parts-Based Volume Mesh
      Simcenter STAR-CCM+ provides a Replace Part operation that allows you to repeat the meshing pipeline with one or more different parts. When the replacement part is defined by a file input from a global parameter, you can use Design Manager to supply the list of filenames during a design study.
    - Replacing a Mesh
      A region associated with a volume mesh in Simcenter STAR-CCM+ can be replaced by another topologically identical volume mesh at any point during the analysis.
    - Extracting Surface Mesh
      The Extract Surface Mesh feature allows you to retrieve the surface mesh after the volume mesh has morphed. This feature allows the volume mesh to be reconstructed with the new shape.
  - Mesh Operations
    Mesh operations perform actions on geometry parts that you can easily repeat whenever their input parts or properties are changed.
  - Mesh Descriptions
    A mesh description is a version of a surface or volume mesh belonging to a geometry part. Geometry parts can have more than one surface mesh description associated with them. You create and change descriptions by importing surfaces or executing operations.
  - Custom Mesh Controls
    Custom controls override any default controls for the surface and volume meshers. This facility allows you to refine or coarsen the mesh for part curves, part surfaces, geometry parts, and specified volumes.
  - Surface Meshers
    Simcenter STAR-CCM+ contains meshing tools which can be used to help prepare a high-quality surface mesh before a volume mesh can be generated.
  - Volume Meshers
    Simcenter STAR-CCM+ contains different types of meshers that can be used to generate a volume mesh starting from a suitably prepared surface mesh.
  - Mesh Refinement
    Simcenter STAR-CCM+ can refine the mesh by approximating the wake region or using solution-based approach. These features allow you to achieve efficient refinement by reducing the cell size in areas of interest.
  - Directed Meshing
    Directed meshing is a method for generating high quality swept meshes on geometries in Simcenter STAR-CCM+. The method operates by sweeping a mesh from the surfaces of a geometry through its volume onto a facing target surface.
  - Two Dimensional and Axisymmetric Meshes
    The use of a one-cell-thick three-dimensional mesh is much less efficient than using a real two-dimensional mesh for two-dimensional and axisymmetric simulations. When circumstances allow, use real two-dimensional meshes.
  - Turbomachinery Mesh
    Turbomachinery applications with axial blades typically require a flow-aligned, structured mesh. This type of mesh has implicit connectivity and a fixed number of vertex or face neighbors, leading to a more accurate solution.
  - Mesh Visualization
    You can visualize any mesh representation in Simcenter STAR-CCM+. After you have imported or generated a mesh, you visualize it to check the cell quality and mesh validity.
  - Checking the Surface Mesh
    The volume mesh quality is directly dependent on the surface mesh quality. Therefore, it is crucial to make sure that all surface meshes are of good quality.
  - Checking the Volume Mesh
    This section describes the tools available for checking the validity and quality of the volume mesh, and for diagnosing problem areas. Such problems can then be fixed, either inside Simcenter STAR-CCM+ or in the originating mesh generator.
  - Meshing Field Functions Reference
    This section contains a list of field functions that are related to meshing.
  - Working With Representations
    This section provides information on representations as a useful part of the meshing process.
  - Scaling the Entire Mesh
    Scaling the mesh is important as the units of the model must be in meters before running an analysis.
  - Working with Baffles
  - Exporting Mesh and Solution Data
    This section outlines the steps for exporting Simcenter STAR-CCM+ mesh and solution data to formats that can be used in other CAE packages.
  - Multi-Region Meshing
    This section outlines the surface requirements for performing multi-region meshing, as well as step-by-step instructions when starting from surface imports that result in single region and multiple regions definitions. Additionally, guidelines are provided on what the best approaches are for exporting surface data from CAD packages when multiple regions are required.

Creating the Surface Wrap Operation and Selecting the Parts to Wrap

Create a Surface Wrapper operation and select the parts to wrap.

To create a Surface Wrapper mesh operation:

Right-click Geometry > Operations and select New > Surface Preparation > Surface Wrapper.
In the Create Surface Wrapper Automated Mesh Operation dialog, select the parts to wrap and click OK.
Unexecuted Surface Wrapper nodes are now displayed under the Geometry > Parts and Geometry > Operations managers.
Select the Default Controls > Base Size and set an appropriate size for the wrap.

Some geometries only require surface wrapping for a portion of their surface. The surface wrapper allows you to exclude part surfaces that you consider sufficiently well tessellated for subsequent mesh operations. For example, the geometry below shows the tessellated surface of a intake manifold. The main body of the manifold is sufficiently refined. However, the channel sections of the manifold, highlighted below, require more surface wrapping.

In cases such as these, wrapping the whole geometry is unnecessary and can defeature highly detailed part surfaces–unless the surface wrapper is excessively refined using custom controls and contact preventions. Instead, you can preserve specified input surfaces and perform partial wrapping.

To exclude specific part surfaces on a geometry from a Surface Wrapper operation and perform partial wrapping:
1. Select the Geometry > Operations > Surface Wrapper node and activate the Perform Partial Wrapping option.
  A Default Controls > Preserved Input Surfaces node appears.
2. Select the Default Controls > Preserved Input Surfaces node and set Excluded Surfaces to all part surfaces that you want to exclude from the wrap.

For partial wrapping, you require the Legacy Wrapper. To run the legacy surface wrapper:

Select the Operations > Surface Wrapper node and activate Legacy Wrapper.
The legacy wrapper operation always runs using shared memory parallelism unless you set the Mesher Execution Mode to Concurrent. For Concurrent execution, each wrapping operation runs in serial.