Stability Analysis of Coupled Simulation

Simulation involving several numerical integrators in parallel is necessary in many situations and at times also advantageous compared to using one central integrator. The solution de-coupling introduced by this coupled simulation is positive for development of complete systems containing several engineering domains. These systems can at times not be simulated in one tool, since e.g. existing models can be dependent on the numerical integrator used in the tools in which they reside. However, when several numerical integrators collaborate in a common problem, the error control is no longer functioning on a global level. Special techniques need to be utilized in order to have a stable and accurate simulation. The paper compares a number of solutions where minimum intrusion is needed into the simulation tools used and where tools can be utilized that do not have the possibility to restart a simulation step on external command. These restrictions are necessary for solutions that are to be applied to commercial simulation tools. The conclusion is that the options available for increasing accuracy in coupled simulation without solver or model intrusion are few. Some simple principles are however given and demonstrated successfully.