Unknown variable 'Z' in figure D.3

[henrikt-ma]

In figure D.3 Example series connection of multiple models with stream connectors., the sensor has a label Z_{3}(min = 0), but there is no use of Z in the surrounding text. Should it be \dot{m}_{3}?

[HansOlsson]

It should be \text{m_flow}_3 or m3.c.m_flow or some variation of this see slide 12 and 27 (bottom) on https://www.modelica.org/education/educational-material/lecture-material/english/ModelicaStream-Overview-Rationale.ppt/view

I understand that they are kind of long, so another solution would be to introduce Z in the text and keep the figure.

If it is intuitively related to dot{m}_{3}, but we should separate the two since the ideal sensor doesn't contain any m (=mass), and if there are multiple ports for a component dot{m} is given by their sum and here we only want the mass-flow through this port.

[henrikt-ma]

OK, how about putting m3.c.m_flow(min = 0) just above the blue box representing the sensor?

[HansOlsson]

OK, how about putting m3.c.m_flow(min = 0) just above the blue box representing the sensor?

Makes sense (after I realized that you meant the "light blue" box), but I realized that there is a major issue in the appendix D: it is using \dot{m} instead of m_flow throughout - without the considerations I gave, whereas chapter 15 uses m_flow. Apart from the problem I stated it's also confusing to have different notations with no explanation.

On the other hand \dot{m} is more common mathematical notation, it's just misleading. I believe we can resolve it by introducing \tilde{m} (or something like that) for m_flow - and have a short explanation for the relation between \tilde{m}and \dot{m}.

[henrikt-ma]

OK, how about putting m3.c.m_flow(min = 0) just above the blue box representing the sensor?

Makes sense (after I realized that you meant the "light blue" box)

Will be fixed as part of #2609.

I realized that there is a major issue in the appendix D: it is using \dot{m} instead of m_flow throughout - without the considerations I gave, whereas chapter 15 uses m_flow. Apart from the problem I stated it's also confusing to have different notations with no explanation.

On the other hand \dot{m} is more common mathematical notation, it's just misleading. I believe we can resolve it by introducing \tilde{m} (or something like that) for m_flow - and have a short explanation for the relation between \tilde{m}and \dot{m}.

Right, that's a bigger issue. Reported separately as #2644.

[HansOlsson]

I finally found the explanation.

Rüdiger Franke did a presentation "Excerpt of Motivation for Modelica stream connectors" as part of "Eurosyslib WP 5.3 Meeting Mannheim, June 9, 2008" (stored in Modelica33 on old svn-server), and used Z instead of m_flow, and included that figure as well.