Physical system modeling with Modelica

Abstract A new language, called Modelica TM , for the modeling of physical systems has been developed in an international effort. The main objective was to make it easy to exchange models and model libraries. The design approach builds on non-causal modeling with true ordinary differential and algebraic equations and the use of object-oriented constructs to facilitate the reuse of modeling knowledge. There are already several modeling languages based on these ideas, available from universities and small companies. There is also significant experience of using them in various applications. The aim of the Modelica effort was to unify the concepts and to design a new uniform language for model representation. The paper describes the effort, gives an overview of Modelica, and demonstrates how Modelica is used in real-world applications: modeling of an automatic gearbox and of a heat exchanger.