Conference article

Stream Connectors - An Extension of Modelica for Device-Oriented Modeling of Convective Transport Phenomena

Rüdiger Franke
ABB AG, Germany

Francesco Casella
Politecnico di Milano, Italy

Martin Otter
DLR Institute for Robotics and Mechatronics, Germany

Michael Sielemann
DLR Institute for Robotics and Mechatronics, Germany

Hilding Elmqvist
Dassault Systèmes (Dynasim), Sweden

Mattson Sven Erik
Dassault Systèmes (Dynasim), Sweden

Olsson Hans
Dassault Systèmes (Dynasim), Sweden

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Published in: Proceedings of the 7th International Modelica Conference; Como; Italy; 20-22 September 2009

Linköping Electronic Conference Proceedings 43:12, s. 108-121

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Published: 2009-12-29

ISBN: 978-91-7393-513-5

ISSN: 1650-3686 (print), 1650-3740 (online)


Modelica 3.0 as well as other physical modeling languages have two basic variable types to describe the interaction of physical components: “Potential” (or across) variable and “flow” (or through) variable. It is shown that with these variable types it is not possible to describe in a numerically sound way bidirectional flow of matter. Other alternatives based on signal flow oriented modeling have severe restrictions how components can be connected together.

This fundamental problem is addressed in Modelica 3.1 by introducing a third type of connector variable for physical systems; called stream variable; declared with the prefix stream.

This article motivates and introduces stream variables. Examples are given for their utilization in basic fluid models.


Thermo-fluid; stream variable; convection; potential/flow variable; across/through variable


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