Export Settings

The following settings appear under the CGNS link node when you set the Transfer Direction to Export.

[Link 1] Conditions and Values

In addition to the general conditions and values (see CGNS Link Reference), the following settings are specific to data export:

Database Format: Specifies the format of the CGNS database files. CGNS has two internal database file formats, HDF5 (with file extension .cgns) and ADF (.cga).
CGNS data was originally stored using ADF (Advanced Data Format), but ADF does not have parallel I/O or data compression capabilities, and does not have the support base and tools that HDF5 offers. ADF has since been superseded by HDF5 (Hierarchical Data Format, Version 5) as the official default underlying storage mechanism for CGNS.

File Mode

Specifies whether Simcenter STAR-CCM+ exports data to a single file or multiple files:

Method	Corresponding Value Nodes
File Series At every export event, Simcenter STAR-CCM+ creates new CGNS files. The files created depend on the specified Mesh Mode. See Output CGNS Files.	File Series Counter Allows you to specify the following properties: Counter Width—specifies the number of digits for the export events counter that is used in the file name. Separator—specifies the character that appears between the base file name and the number of the trigger event (@ by default).
Single File Simcenter STAR-CCM+ creates separate files for mesh and solution data during the first export event (see Output CGNS Files). In subsequent exports, Simcenter STAR-CCM+ appends the export data to the existing files.	None

Mesh Mode

Allows you to restrict mesh data export based on mesh changes:

Always Enabled—Simcenter STAR-CCM+ exports the mesh data at every export event. This option is available only when you set File Mode to File Series.
Initially and on Mesh Change—Simcenter STAR-CCM+ exports the mesh data in the first export event. In subsequent exports, Simcenter STAR-CCM+ exports mesh data only when the mesh changes.

Time Range

This condition is only available if the Interval Trigger is set to Time Step or Delta Time and allows you to restrict data export to a specified time range:

Method	Corresponding Value Nodes
Always Enabled Data export is active throughout the entire simulation.	None
Enable After Start Time Data export starts after a specified time.	Start Time Specifies the time at which data export starts.
Enable Before Stop Time Data export stops at a specified time.	Stop Time Specifies the time at which data export stops.
Enable Between Start and Stop Times Data export is active within a specified time range.	Start Time, Stop Time Specify the times at which data export starts and stops, respectively.

No data is exported from the CGNS file set when either of the following conditions are met:

The current Simcenter STAR-CCM+ physical time is less than the specified Start Time.
The current Simcenter STAR-CCM+ physical time is greater than or equal to the user specified Stop Time.
Simcenter STAR-CCM+ has reached the end of the available CGNS file set import states.

Interval Trigger

Specifies the trigger method for the automatic execution of export events. The available options are:

Method	Corresponding Value Nodes
None Automatic export of CGNS data is deactivated.	None
Time Step Allows you to specify the export frequency as number of time-steps between exports.	Time Step Frequency Specifies the number of time-steps between two consecutive export events.
Delta Time Allows you to specify the time interval between exports.	Delta Time Specifies the time interval between two consecutive export events.

To enable automatic export the Interval Trigger node must be set to either Time Step or Delta Time.

Mapping Option: If set to Map Before Export, the field data is mapped from the internal region and boundaries to the external region and boundaries. If you have not set any External Continua this property will be read only. The external continuum must contain the File Transfer and CGNS Data Fileset models. By mapping before export it is possible to reduce the overall data output size by, for example, mapping from a fine to a coarse mesh, or by mapping from a moving to a static mesh.

Connection to File (Read-Only): Displays the state of data export and the output file name.

File

Specifies the details for the output CGNS files:

Directory—location in which Simcenter STAR-CCM+ saves the CGNS files.
Base Filename—name prefix used in the file name. The default base filename is solution. The resulting file name depends on the specified File Mode and Mesh Mode (see Output CGNS Files).

Fields Export Precision

Specifies the level of precision of the exported CGNS file as either:

Single Precision—exports the field data in single precision. The exported field data is half the size compared to Double Precision.
Double Precision—exports the field data in double precision.

[Zone] Conditions and Values

The zone conditions and values specify the parts (either boundaries or regions) from which Simcenter STAR-CCM+ exports data and the fields that are exported.

Boundary Triangulation

Controls how Simcenter STAR-CCM+ treats polygonal mesh faces when exporting surface meshes. Simcenter STAR-CCM+ can retain polygonal meshes or convert them to triangular meshes. Triangulating polygons is useful when you want to import the CGNS file into software packages that do not support polygonal meshes (for example, in finite element packages). Set Option to one of:

Do Not Triangulate—retains the original polygonal faces.
All Faces Including Quads—converts all polygonal faces to triangular faces.
All Faces Excluding Quads—converts all polygonal faces to triangular faces while retaining quadrilateral faces. In general, most software packages (including finite element packages) support quads. Not triangulating quadrilateral faces leads to smaller file sizes.

Exported Fields

Allows you to export scalar or vector fields to the CGNS file. To export a field, you add an auxiliary field of appropriate type (scalar or vector) and set its properties:

Initialization Method: Automatically set to User-specified Initialization Value. Specify a constant initialization value under the [Link 1] > Zones > [Zone] > Values > Initialization Values node.

Field Stencil: Specifies the mesh stencil (Vertex or Face for surface meshes, and Vertex or Cell for volume meshes) from which Simcenter STAR-CCM+ maps the field data to be exported.; Depending on the field specification, you can either select the field native stencil or a different stencil. The native stencil is the location where Simcenter STAR-CCM+ computes the solution—its type depends on the specific field. For example, Simcenter STAR-CCM+ computes the pressure field at mesh faces, whereas the displacement field is computed at mesh vertices. When exporting data from the field native stencil, Simcenter STAR-CCM+ exports the original solution as computed at the native stencil. When exporting data from a different stencil, Simcenter STAR-CCM+ exports the solution data interpolated to the chosen stencil.

Field Treatment (Read-Only): Automatically set to Unmanaged.

Scalar/Vector Function: Specifies the scalar or vector field function that stores the data to be exported.; As CGNS only supports scalar fields, Simcenter STAR-CCM+ exports vector fields as separate scalar fields for each component. The name of each scalar field is the specified auxiliary feld name followed by the component. For example, a vector auxiliary field named Velocity is exported as three scalar fields named VelocityX, VelocityY, and VelocityZ.

Merge Boundaries

Controls whether Simcenter STAR-CCM+ retains the original boundaries when exporting surface meshes:

Option	Corresponding Value Node
Do Not Merge Boundaries Retains the original boundaries.	None
Merge Boundaries Into One Merges the original boundaries into a single boundary.	Merged Boundaries Name Specifies the name for the resulting boundary.

Volume Parts: Specifies the Simcenter STAR-CCM+ regions for export of mesh and solution data.

Surface Parts: Specifies the Simcenter STAR-CCM+ boundaries for export of mesh and solution data.

Exported Volume Parts: Specifies the regions to be used to store the mapped volume partner mesh data when Map Before Export is selected.
Exported Surface Parts: Specifies the boundaries to be used to store the mapped surface partner mesh data when Map Before Export is selected.

Output CGNS Files

The following table shows the expected output files for different combinations of File Mode and Mesh Mode settings, when exporting mesh and solution data or mesh data only. All other settings (such as the database format and the base filename) have the default values.

Table 1.
File Mode	Mesh Mode	Exported Fields	Example Output Files	Description
File Series	Always Enabled	None	solution@mesh00001.cgns solution@mesh00002.cgns [...]	Each file contains mesh data only.
	Always Enabled	Specified	solution@00001.cgns solution@00002.cgns [...]	Each file contains both mesh and solution data.
	Initially and on Mesh Change	None	solution@mesh00001.cgns solution@mesh00003.cgns [...]	Each file contains mesh data only.
	Initially and on Mesh Change	Specified	solution@mesh00001.cgns solution@00001.cgns solution@00002.cgns solution@mesh00003.cgns solution@00003.cgns solution@00004.cgns [...]	Mesh and solution data are exported to separate files. The solution data files link to the correct mesh file.
Single File	Initially and on Mesh Change	None	solution@mesh1.cgns	Mesh data are exported to a single file. If the mesh changes during the simulation, an additional base node is created in the mesh file.
Single File	Initially and on Mesh Change	Specified	solution@mesh1.cgns solution.cgns	Solution and mesh data are exported to separate files. At each export event, the solution data set is added to the same base node within the solution data file. If the mesh changes during the simulation, an additional base node is created in the mesh file. The solution data sets link to the relevant mesh base node.