Limitations

Compatibility with other operating systems and CPU architectures

Limitations In order for the co-simulation to successfully run, both the 1D and the CFD models must be compiled for the same operating system (Windows or Linux) and CPU architecture (32-bit or 64-bit). Failing this, the co-simulation will not run.

Note

Most CFD codes today run on networked or clustered Linux or Windows 64 bit simulation set-ups.   Simcenter Amesim supports the compilation of models for 64-bit Linux systems since Rev 13 SL3, and for 64-bit Windows systems since Rev 8B. Models created in those versions or ulterior versions of Simcenter Amesim (depending on the operating system) can be used to create a co-simulation DLL compatible with that OS/architecture configuration.

Availability of some features on the CFD side

Some features of the Simcenter Amesim platform have limited or no functionality when it comes to interfacing with CFD software.   For instance, stabilizing runs can still be performed on the 1D side, but are difficult to perform in conjunction with CFD. Indeed, it would require the CFD to run and converge to a steady-state steady state  solution for each potential 1D equilibrium equilibrium  point, which would be very time consuming, if at all possible.

Note

Please refer to Support for Simcenter Amesim Platform features in the context of 1D/3D CFD co-simulation in the context of 1D/3D CFD co-simulation for more information and details about which features are currently supported by Simcenter Amesim.

Heterogeneous co-simulation and multiple instantiation

• Multiple interfaces and heterogeneous co-simulation

It is easy to imagine a scenario where a model would contain multiple interfaces to companion software. For example, when modeling a solenoid injector, the user might want to simulate the electrical actuation part of the model in a dedicated FEM package, and the nozzle flow in the companion CFD software.   This can be done in a straightforward manner in Simcenter Amesim. Indeed, users can include multiple interfaces with third-party software in the model: Functional Mockup Interfaces (FMIs), Simcenter 3D Motion, Simulink interfaces, and so on. The model can also contain and simulate Modelica submodels.   That being said, this configuration is best-suited to the “tool coupling” scenario – i.e. the case where all the software involved are present on the same machine. Additionally, as this set-up would most likely imply the import of one or several DLLs, users must take care to ensure that these DLLs can be successfully retrieved and loaded into the 1D model. For this reason as well, the set-up would be made simpler if implemented on one same machine. In addition, simulating a model which incorporates several software interfaces could involve higher chances of encountering instabilities in the co-simulation. As the co-simulation time-step is only managed between the CFD companion package and the Simcenter Amesim solver, the other interfaces are not taken into account as the co-simulation time-step is varied, which could generate instabilities in some cases.   Users must additionally note that the cross-platform aspect, mentioned at the beginning of this section, applies here as well. Cross-platform compilation is not supported, so all models involved must be compiled for the same operating system and CPU architecture.

• Multiple export

In 1D/3D CFD co-simulation, the Simcenter Amesim model is generally exported as a “UserCosim” DLL to the companion CFD software package. This exported DLL can only be imported into one receiving software package at a time – meaning, it is impossible to run a co-simulation between this Simcenter Amesim DLL and multiple CFD packages simultaneously.

• Multiple instantiation

Users may in some cases want to include several instances of one same Simcenter Amesim model in a co-simulation with the CFD software package. As the exported DLLs would all have the same filename, it will be impossible to distinguish between the different instances of the model, therefore preventing the co-simulation from succeeding. You must therefore carefully name the different instances of your 1D model to avoid the scenario described here.