Co-Simulation Zones Reference

You can define multiple co-simulation zones to apply different conditions on different sets of coupled boundaries. The fields that are exchanged between the codes, and the mapper settings, are set independently for each co-simulation zone.

A coupling zone can be set up for surface-to-surface coupling, to exchange data between Simcenter STAR-CCM+ boundaries and Abaqus surfaces, or surface-to-point coupling, for data exchange between Simcenter STAR-CCM+ boundaries and a node on the Abaqus model.

Zones Manager Properties

Number of Zones

Displays the number of zones defined for this link. Read-only.

Zones Manager Right-Click Actions

New

Adds a co-simulation zone under the Zones node.

Zone Properties

Index

Specifies a unique index which identifies a zone. A zone is connected with the zone of same index in the partner simulation. Read-only.

Zone Type

Specifies what type of Simcenter STAR-CCM+ objects are assigned to the co-simulation zone for coupling. The available option is Surface Zone.

Zone Conditions and Values

The conditions and values of a co-simulation zone allow you to specify the coupled boundaries and the fields that are exchanged during the co-simulation.

Mapper Settings

Allows you to specify the settings that control mapping of data between the fluid and the structural mesh. A separate mapping operation is done for each type of exchanged field (displacement and temperature versus traction and heat flux) and each direction of mapping (imported versus exported). For fields exported to Abaqus, the fluid boundary acts as a source and the structure surface acts as a target. For fields imported from Abaqus, the structure surface acts as a source and the fluid boundary acts as a target.

The available mapping controls are:

Proximity Tolerance -- In surface-to-surface coupling, this option specifies the relative search distance to use in the initial search. If Simcenter STAR-CCM+ mappers are used, the distance is relative to the maximum face size on the coupled boundary source surface. If Abaqus mappers are used, the distance is relative to the average face size on the coupled boundary source surface. This option is not used in surface-to-point coupling, where all the vertices and faces of the Simcenter STAR-CCM+ coupled boundaries are included in the mapping operation. You can increase the proximity tolerance to resolve small mismatches. However, arbitrarily increasing the proximity tolerance can mask errors in the model setup by allowing the search to find neighbors that are not in close proximity. Matching neighbors that are not in close proximity leads to incorrect results.

Check Normals -- In surface-to-surface coupling, this option checks that the Simcenter STAR-CCM+ boundary and Abaqus surface are oriented toward one another in the initial search in the mapper. This option is not used in surface-to-point coupling. In cases where initial search failures occur due to discretization differences in areas of large curvature variation, you can deactivate the normal check.

Mapping Rotations -- In surface-to-surface coupling, when you activate this option the mappers add a rotational correction to the displacement mapped on the target surface if this is offset from the source surface. When the source surface undergoes large rotations, activate this option to preserve the shape of the fluid surface as the structure rotates. Deactivate this option when the structure in Abaqus is modeled using shell elements and the deformation causes the physical shell surface to self-intersect during the analysis. In surface-to-point mapping, this option controls whether rotations of the Abaqus node are also imported, and resultant moments exported.

Coupled Model Parts

Displays the boundaries on the Simcenter STAR-CCM+ model that exchange data with Abaqus, through this co-simulation zone.

This property is read-only. To assign a Simcenter STAR-CCM+ boundary or region to a co-simulation zone, use the External Code Coupling Specification boundary condition.

Exported Fields, Imported Fields

Allow you to specify the fields that are exchanged with Abaqus. For more information, see Exchanged Fields Reference. When you export traction fields, you can adjust the exported traction using the Values > Exported Traction Field Controls node. See Exported Traction Field Controls.

External Part Settings

Allows you to define the required setting to couple an Abaqus region to the Simcenter STAR-CCM+ zone. The available properties are:

Abaqus Region Name: Specifies the name of the Abaqus region that couples with the Simcenter STAR-CCM+ zone. The specified name must be a valid surface, node set, or element set in your Abaqus model, as defined in the corresponding Abaqus input file or the job_modelDescription.xml file generated by the Abaqus Co-Simulation engine.

Abaqus Region Type: Specifies whether the boundaries that are assigned to this zone couple with an Abaqus surface or node.

Use Zone Name as Region Name: When active, sets the Abaqus Region Name to the [Zone] name. If you change the [Zone] name the Abaqus Region Name is automatically updated.

Local Values (For Implicit Coupling Only)

Allows you to select the values that are monitored during the simulation.

Traction Export Option

Allows you to select the method by which the pressure component of traction is exported. The available options are:

Pressure Field: Exports the pressure as a scalar field pressure.

Concentrated Force: Converts the scalar pressure field into the respective forces on the vertices of the mesh and exports it as a vector field.

The Traction Export Option is only available if Pressure, Wall Shear Stress, or both are exported under the Exported Fields node. The Traction Export Option is also limited to Concentrated Force if the following cases:

• When both Pressure and Wall Shear Stress are added to the Exported Fields node.
• When using the Abaqus Explicit Coupling solver.
• If the Partner Zone Type is set to Point Zone.

Stabilization Options (For Implicit Coupling Only)

Specifies the type of stabilization applied to the imported fields of the co-simulation. The five Options and their corresponding Value nodes and properties are:

Options	Corresponding Value Nodes
Constant	Constant URF Applies a fixed under-relaxation factor. The properties are: First Iteration URF—read only, set to default value of 1.0. Second Iteration URF—allows you to specify the under-relaxation value of the second inner iteration of the implicit coupling range. This value is also used for the remaining iterations.
Adaptive	Adaptive URF Applies an under-relaxation factor calculated by Aitken's delta squared method [143]. The properties are: First Iteration URF—read only, set to default value of 1.0. Second Iteration URF—allows you to specify the under-relaxation value of the second inner iteration of the implicit coupling range. Adaptive URF Range—allows you to specify the maximum and minimum values for the under-relaxation factor. Adaptive URF Increment—allows you to specify the increment by which the adaptive under-relaxation factor can increase or decrease.
Constant - Expert	Constant URF - Expert Similar to Constant, however allows you to control the first Iteration URF. The properties are: First Iteration URF—specifies the under-relaxation value for the first inner iteration of the implicit coupling range. Second Iteration URF—specifies the under-relaxation value of the second inner iteration of the implicit coupling range. This value is also used for the remaining iterations.
Adaptive - Expert	Adaptive URF - Expert Similar to Adaptive, but allows you to control the first iteration URF. The properties are: First Iteration URF—allows you to specify the under-relaxation value for the first inner iteration of the implicit coupling range. Second Iteration URF—allows you to specify the under-relaxation value of the second inner iteration of the implicit coupling range. Adaptive URF Range—allows you to specify the maximum and minimum values for the under-relaxation factor. Adaptive URF Increment—allows you to specify the increment by which the adaptive under-relaxation factor can increase or decrease.
Anderson Acceleration	Anderson Acceleration Applies the Quasi-Newton Anderson acceleration method (see Anderson Acceleration). Anderson acceleration is available as an under-relaxation option for implicitly coupled problems with the Abaqus co-simulation model. Enabling this option can improve convergence for strongly coupled FSI problems. The properties are: First Iteration URF—read only, set to default value of 1.0. Second Iteration URF—allows you to specify the under-relaxation value for the second inner iteration of the implicit coupling range. A value of 0.1 is recommended. Filtering Parameter—allows you to filter out linearly dependent increments of fixed-point residuals (see the term ${\mathbf{F}}_k$ in Eqn. (4640)). If too many vectors are filtered. the solution may not converge, or it may converge slowly. However, if the linear dependencies are not filtered out, the numerical solution of the least-squares problem can become unstable. A value of 10E-6 is recommended for an initial run. History Size—allows you to set the maximum number of increments that approximate the Jacobian. Corresponds to the value $m$ in Eqn. (4639). Time Steps Reused—specifies the maximum number of time-steps Simcenter STAR-CCM+ reuses to accelerate the convergence of transient simulations, assuming that the fixed-point problems are closely related. A value of 5 is recommended for an initial run. Note Anderson Acceleration is only available when the Coupling Negotiation Option is set to Export.

Tolerance (For Implicit Coupling Only)

Specifies the tolerance for assessing convergence of all fields imported from Abaqus. Within a time-step, the exchanges between Simcenter STAR-CCM+ and Abaqus terminate when the displacement or temperature residual reaches the specified tolerance, or when the maximum number of inner iterations is reached.

Zones Conditions and Values Right-Click Actions

Object	Right-Click Actions
Conditions > Local Values	Add Local Values Allows you add the respective URF value monitors to the simulation tree. There are 2 options: Displacement URF Temperature URF It is important to note that you can only add one of each value. And the properties for both are set.