MOSILAB - a Modelica solver for multiphysics problems with structural variability

Frequently, systems showing time-continuous as well as time-discrete behavior arise in multi-physics problems. Simulators supporting the dynamic simulation of hybrid systems often can deal with simple model variations only. A fundamental change of the model structure such as adding or removing differential or algebraic equations (structural variability) is not possible with most simulators. Unlike presently available Modelica simulators, Mosilab can be used to describe systems with inherent dynamics of the model structure, i.e. systems whose mathematical structure can change during simulation. Within Mosilab, the modeling language Mosila is used which is essentially Modelica with an extension based on statecharts for the mapping of state dependent changes of the model structure. Several numerical solvers can be used for simulation. Because events changing the state of the system may appear, the solvers have to fulfil certain requirements such as calculating consistent initial conditions after entering a new state of the chart. Recently, this calculation has been improved for the IDA solver which will be shown for a simple example. A further example with structural variability and its solution by Mosilab is presented.