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How does Dymola set up the system of equations from the created equations and selected parameters in the components and how is this solved?

How does Dymola set up the system of equations from the created equations and selected parameters in the components and how is this solved? Is there any literature with illustrations or examples?

I am trying to figure out how the system of equations is set up and solved. I want to know what influence the different calculation methods have on my results.

Solution

  • The question is very general, so potentially the best answers is general literature. They keywords you are looking for to feed your favorite search engine are likely:

    1. Symbolic preprocessing: it does transform equations (which most Modelica models are built from) to assignments which are common in programming and can be compiled directly. This results in an executable model.
    2. Numeric integration: Uses the outputs of the model (among others, derivatives of state variables) and integrates them to estimate future values of states.

    I would suggest to take a look a the following openly available sources regarding symbolic preprocessing. For numerical integration there should be quite a lot of material available as it is more common...

    1. Claytex blog: https://www.claytex.com/tech-blog/model-translation-and-symbolic-manipulation/
    2. A bit more detailed and with a different approach: Lecture by Prof. Cellier, especially slide decks 4-6: https://people.inf.ethz.ch/fcellier/Lect/MMPS/Ppt/mmps_ppt_engl.html