GT-SUITE Co-Simulation

Simcenter STAR-CCM+ allows for two-way co-simulation with GT-SUITE, a multiphysics simulation tool from Gamma Technologies. GT-SUITE provides a modeling framework for the design and analysis of engineering systems, such as engines, vehicles, and thermal-hydraulic networks.

During the co-simulation, GT-SUITE drives the overall one-dimensional system simulation, while Simcenter STAR-CCM+ models the flow within components that require a three-dimensional analysis. For example, you can use Simcenter STAR-CCM+ to model an intake manifold that forms part of an engine analysis designed in GT-SUITE.

Co-Simulation Interface

In GT-SUITE, you define the co-simulation interface using the following objects:
  • CFD Component—represents the component that is modeled in 3D using Simcenter STAR-CCM+.
  • CFD Interfaces—mark the 1D/3D interfaces between GT-SUITE and Simcenter STAR-CCM+.
  • CFD Connections—define the physical conditions and values at the 1D/3D interfaces.
In Simcenter STAR-CCM+, you couple the relevant boundaries with GT-SUITE using co-simulation zones. Each co-simulation zone uniquely associates a GT-SUITE CFD connection with a Simcenter STAR-CCM+ boundary.

Co-simulation zones and CFD connections must match in number and name.

Exchanged Fields

Co-simulation supports coupling between CFD connections (either CFDFlowConn or CFDFlowConnBeta connections) and Simcenter STAR-CCM+ boundaries of type Mass Flow Inlet, Velocity Inlet, or Pressure Outlet.

The fields that are exchanged between the CFD connection and the coupled Simcenter STAR-CCM+ boundary depend on:
  • the Simcenter STAR-CCM+ boundary type
  • the GT-SUITE CFD Interface Condition that you define for the CFD connection
Simcenter STAR-CCM+ Boundary Type GT-SUITE CFD Connection GT-SUITE CFD Interface Condition Imposed by GT Imported from GT-SUITE Exported to GT-SUITE
Velocity Inlet CFDFlowConn Flow (velocity or mass flow rate)
  • Velocity
  • Static Pressure
CFDFlowConnBeta Flow (CFD imposes GT pressure): Velocity
Mass Flow Inlet CFDFlowConn Flow (velocity or mass flow rate)
  • Velocity
  • Density
  • Static Pressure
CFDFlowConnBeta Flow (CFD imposes GT pressure): Velocity
Flow (CFD imposes GT pressure): Mass Flow Rate
  • Mass
Pressure Outlet CFDFlowConn Pressure Depending on the flow direction, either:
  • Static Pressure, when flow is leaving the Simcenter STAR-CCM+ boundary
  • Total Pressure, when flow is entering the boundary
  • Velocity
CFDFlowConnBeta Pressure (CFD imposes GT velocity)
Pressure (CFD imposes GT mass flow)
  • Mass

At a Mass Flow Inlet boundary, Simcenter STAR-CCM+ applies the mass flow rate that is calculated from the imported fields (either velocity and density, or mass).

Depending on the flow direction, Simcenter STAR-CCM+ also imports or exports the following fields, regardless of the type of coupled boundary and CFD connection:
Flow Direction Imported from GT-SUITE Exported to GT-SUITE
Entering the Simcenter STAR-CCM+ boundary
  • Temperature
  • Mass Fractions
--
Leaving the Simcenter STAR-CCM+ boundary --
  • Temperature
  • Mass Fractions
  • Passive Scalars

At a Mass Flow Inlet boundary, Simcenter STAR-CCM+ applies the total temperature that is calculated from the imported static temperature and velocity. At a Velocity Inlet boundary, Simcenter STAR-CCM+ directly applies the static temperature imported from GT-SUITE.

GT-SUITE and Simcenter STAR-CCM+ do not exchange turbulence values. Turbulence values are specified in Simcenter STAR-CCM+ at the boundary level, in the usual manner.

Before sending data back to GT-SUITE, Simcenter STAR-CCM+ averages the computed fields across sampling volumes adjacent to the coupled boundaries, to convert the three-dimensional fields to one-dimensional values. Volume averaging is important when significant three-dimensional effects occur near the coupled boundary. The co-simulation provides optimum results when the flow in the sampling volumes is approximately one-dimensional.

GT-SUITE co-simulation uses an explicit coupling scheme, that is, data exchange occurs once per time-step.

Multi-Component Gases: Coupled Material Components

In co-simulation with GT-SUITE you can model single-component gases and liquids, and multi-component gases. When you model multi-component gases, GT-SUITE defines the components of the fluid mixture in the co-simulation. These components include unburned species and burned species, which result from the products of reaction between the unburned species. The combustion products consist of 13 components with varying composition:
  • prod_ar: Argon
  • prod_co: Carbon Monoxide
  • prod_co2: Carbon Dioxide
  • prod_h: Monatomic Hydrogen
  • prod_h2: Hydrogen
  • prod_h2o: Water
  • prod_n: Monatomic Nitrogen
  • prod_n2: Nitrogen
  • prod_no: Nitric Oxide
  • prod_o: Monatomic Oxygen
  • prod_o2: Oxygen
  • prod_oh: Hydroxide
  • prod_so2: Sulphur Dioxide

You associate the GT-SUITE species with corresponding mixture components or passive scalars in Simcenter STAR-CCM+. Mixture components represent GT-SUITE species that influence the bulk flow, that is, species that have non-trace quantities. Passive scalars represent GT-SUITE species that do not influence the bulk flow, that is, species that have trace quantities.

The species mass fractions are exchanged at the co-simulation interface, as described in the previous section.

GT-SUITE Coupling Libraries

In order to communicate with GT-SUITE, Simcenter STAR-CCM+ requires the location of the double precision GT-SUITE coupling library. By default, the coupling library file is located at:
Platform Library File Location
Linux [GTIHOME]/[GT-SUITE_version]/GTsuite/bin/linux_x86_64/coupling/libgtlink_dp.so
Windows [GTIHOME]/[GT-SUITE_version]/GTsuite/bin/win64/coupling/gtlink_dp.dll

where [GTIHOME] is the path to the GT-SUITE installation and [GT-SUITE_version] is the version of GT-SUITE.