Conference article

Initial Value Calculation for DAE with Higher Index

Andreas Uhlig
ITI GmbH, Germany

Torsten Blockwitz
ITI GmbH, Germany

Uwe Schnabel
ITI GmbH, Germany

Tobias Nähring
ITI GmbH, Germany

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

Linköping Electronic Conference Proceedings 43:25, s. 233-242

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Published: 2009-12-29

ISBN: 978-91-7393-513-5

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


The solution of Differential-Algebraic Equations (DAEs) requires the calculation of initial values at the beginning of the simulation as well as after discontinuities. An approach is described that allows consistent initial value calculation (IVC) for higher index DAE with structural changes. To consider rigid impacts integral equations for the conservation of momentum are automatically generated. The method includes handling of fixed initial values and the observance of feasible regions.


Initial Value Calculation; DAE; Index calculation; Impulsive Distribution


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