FMU Link Reference

In Simcenter STAR-CCM+, you specify the settings for co-simulation in a link node under the External Links node.

A link node, External Links > [Link 1], appears automatically in the simulation tree when you create an external physics continuum. You can also create an FMU link manually through the [Imported Library] node right-click menu (see FMI Library Reference). This node represents a connection to an external application and allows you to specify the settings for co-simulation.

[Link 1] Properties

Link Type: Describes the type of connection. Read-only.
Link Priority: Specifies the order in which the links are executed.

Link Models

In a Simcenter STAR-CCM+ simulation, you access the co-simulation framework by activating co-simulation models in the physics continua. These models determine the physics of the coupling, including the fields that can be exchanged with the partner simulation.

Link models configure the connection to a partner application or file. The link icon changes based on the application, or file, that Simcenter STAR-CCM+ connects to through the link. The link model must be appropriate for the co-simulation or file export model selected in the physics continuum.

[Link 1] Conditions and Values

You specify the general settings of the co-simulation under the [Link 1] > Conditions and [Link 1] > Values nodes.

FMI Version

Specifies the version of the FMI standard on which the FMU is based. Simcenter STAR-CCM+ supports version 1, 2, and 3 of the FMI standard. For more information, see the official website.

Load Partner Library, Launch Partner Option, Connect Option

These options specify which method the simulation uses to launch the external application and connect. Simcenter STAR-CCM+ automatically sets these options to the methods that are compatible with FMU Co-simulation.

Concurrency Mode

Allows you to specify which simulation runs first when the co-simulation starts.

Lead—Simcenter STAR-CCM+ runs first and, when the exchange criteria are met, it sends data to the FMU.
Lag—Simcenter STAR-CCM+ waits for data from the FMU before running.
Concurrent—Simcenter STAR-CCM+ and the FMU start at the same time and run simultaneously.

Coupling Negotiation Option

Specifies the method to determine the time interval between data exchanges. The following methods are available:

Method	Corresponding Value Nodes
Matched Coupling Time The simulations exchange data at a specified time interval. The time interval between exchanges is the same in both simulations.	Transfer Interval Specifies the time interval between data exchanges. Make sure that you enter a value that is equal or grater than the simulations time-step.
Time-Step The simulations exchange data at a time interval equal to the Simcenter STAR-CCM+ simulation time-step. The time interval between exchanges is the same in both simulations.	Transfer Interval Displays the time interval at which data is exchanged. Read-only.

Time-Step Adjustment Option

Specifies how Simcenter STAR-CCM+ adjusts the simulation time-step when the remaining time to the next coupling point is not an exact multiple of the simulation time-step. For more information, see Time-Step Adjustment Option for Simcenter STAR-CCM+ Co-Simulation.

Verbosity Level

Controls the amount of information that is printed to the Output window.

External Continua

Allows you to select the external physics continuum that represents the FMU model.

FMI Interactive

FMU models can be solved by an external application, which acts as a simulator. This option allows you to select the method for launching the external simulator:

Start Automatically—Simcenter STAR-CCM+ automatically launches the external simulator when required by the FMU.
Start Manually—you are responsible for launching the external simulator manually.

FMI Visibility

For FMU models that require an external simulator, this option allows you to choose whether the simulator is executed in:

Batch Mode—the external simulator runs in the background. The application user-interface is not visible.
Interactive Mode—the external simulator is launched with its user-interface.

FMI Logging

FMU instances typically output their own log, which provides information on the FMU solution process. This option allows you to control the amount of information from the FMU that is printed to the Output window.

FMI Resource Reference

Specifies the FMI Library that is associated with the link.

Exported Values

Contains nodes that specify the values that are exported to the FMU. Values under this node (and not under a zone) are generally useful for exporting general data, rather than quantities that are computed at boundaries or regions.

Exported value nodes have the following properties:

Initialization Method—automatically set to User-specified Initialization Value. Specify a constant initialization value under the Link > Values > Initialization Values node.
Field Treatment—automatically set to Unmanaged. This setting indicates that Simcenter STAR-CCM+ does not perform any operation on this value before export.
Value—allows you to specify the value that is exported to the FMU. Although you can export any data type supported by FMU (real, integer, boolean, string, enumeration), you typically export scalar quantities of type real. For more information, see Specifying the Scalar Values Exchanged with the FMU.
As FMU variables are spatially-invariant, Simcenter STAR-CCM+ must export single-value data.

Imported Values

Contains nodes that specify the values that are imported from the FMU. Values under these nodes (and not under a zone) are generally useful for importing data that are not necessarily applied to boundaries or regions. The imported values are stored as single values. Imported value nodes have the following properties:

Initialization Method—automatically set to User-specified Initialization Value. Specify a constant initialization value under the Link > Values > Initialization Values node.
Value—displays the imported value. This property is read-only and is updated when Simcenter STAR-CCM+ receives data from the FMU. Simcenter STAR-CCM+ stores this value with the name [Link 1].[FMU variable name]. You can reference this value when writing expressions.

Parameters

Contains nodes that allow you to set the parameters that are defined in the FMU. Depending on the parameter data type, which is defined by the FMU, you specify the parameter Value using either an integer, real, enumeration, string, or boolean. For more information, see Specifying the Scalar Values Exchanged with the FMU.

Tracked Values

Contains nodes that display local variables of the FMU that you can monitor in Simcenter STAR-CCM+. You cannot set FMU local variables in Simcenter STAR-CCM+.

Co-Simulation Progression

Displays the current stage in the co-simulation.

FMU Connection State

Displays the state of connection between the simulations.

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. Read-only.
Zone Type: Specifies what type of Simcenter STAR-CCM+ objects are assigned to the co-simulation zone for coupling. In co-simulation with FMU the available options are Surface Zone, Volume Zone, and Shell Zone.

[Zone] Conditions and Values

The conditions and values of a co-simulation zone allow you to specify the Simcenter STAR-CCM+ coupled model parts (either boundaries or regions) and the quantities that are exchanged during the co-simulation.

Coupled Model Parts

Displays the Simcenter STAR-CCM+ boundaries or regions that exchange data with the FMU through this co-simulation zone. This property is read-only. To assign a model part to a co-simulation zone, use the External Code Coupling Specification condition for the relevant boundary or region.

Exported Values

Contains nodes that specify the values that are exported to the FMU through the co-simulation zone. As FMU variables are spatially-invariant, Simcenter STAR-CCM+ must export single-value data. Values exported through a co-simulation zone typically represents single-value averages of fields that are computed at the coupled model parts.

Exported value nodes have the following 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.
Value—allows you to specify the value that is exported to the FMU. Although you can export any data type supported by FMU (real, integer, boolean, string, enumeration), you typically export scalar quantities of type real. For more information on setting values according to the data type, see Specifying the Scalar Values Exchanged with the FMU.

Imported Fields

Contains nodes that specify the fields that are imported from the FMU through the co-simulation zone. Values that are imported from the FMU through a co-simulation zone are stored as spatially-uniform fields that can be used to set conditions on boundaries or regions. Imported field nodes have the following 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 stencil on the Simcenter STAR-CCM+ coupled model parts (either Vertex, Face, or Cell) to which Simcenter STAR-CCM+ maps the imported field.
Field Treatment—automatically set to Unmanaged. This setting indicates that you are responsible for setting the relevant boundary or region conditions manually, using the field functions that store the imported fields.
Scalar Function—displays the name of the field function that stores the spatially-uniform field constructed from the imported value. The field function name is of the format Co-Simulation: [FMU variable name]. Use this field function when setting boundary or region conditions.

Link Right-Click Actions

Create New Zone: Allows you to create a new zone within an existing link.