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
Ladda ner artikel
http://dx.doi.org/10.3384/ecp09430078Ingår i: Proceedings of the 7th International Modelica Conference; Como; Italy; 20-22 September 2009
Linköping Electronic Conference Proceedings 43:12, s. 108-121
Publicerad: 2009-12-29
ISBN: 978-91-7393-513-5
ISSN: 1650-3686 (tryckt), 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
[1] R.P. Brent (1973): Algorithms for Minimization without derivatives. Prentice Hall; pp. 58-59.
[2] F. Casella; A. Leva (2003): Modelica open library for power plant simulation: design and experimental validation. Proceedings of the Modelica 2003 Conference; editor: P. Fritzson; Linköping; Sweden. www.modelica.org/events/Conference2003/papers/h08_Leva.pdf
[3] Dymola (2009). Dymola Version 7.2. Dassault Systèmes; Lund; Sweden (Dynasim). www.dymola.com
[4] H. Elmqvist; H. Tummescheit; M. Otter (2003): Object-Oriented Modeling of Thermo-Fluid Systems. Proceedings of the Modelica 2003 Conference; editor: P. Fritzson; Linköping; Sweden. www.modelica.org/events/Conference2003/papers/h40_Elmqvist_fluid.pdf
[5] R. Franke; F. Casella; M. Sielemann; K. Proelss; M.Otter; M. Wetter (2009): Standardization of thermo-fluid modeling in Modelica.Fluid. Proceedings of the Modelica 2009 Conference; editor: F. Casella; Como; Italy. www.modelica.org/events/modelica2009
[6] Modelica (2009): Modelica Language Specification; Version 3.1. www.modelica.org/documents/ModelicaSpec31.pdf
[7] H. Olsson; M. Otter; S.E. Mattsson; H. Elmqvist (2008): Balanced Models in Modelica 3.0 for Increased Model Quality. Proceedings of the Modelica 2008 Conference; editor: B. Bachmann; Bielefeld; Germany. www.modelica.org/events/modelica2008/Proceedings/sessions/session1a3.pdf
[8] SimulationX (2009). SimulationX Version 3.2. ITI; Dresden; Germany. www.simulationx.com
