Remaining issues with HelmholtzMedia in OpenModelica

[thorade]

newInst Library report, Library coverage, last 7 runs

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This is a follow-up ticket for #34, to track the few issues that are left after the release of OpenModelica 1.16.
There is a corresponding ticket in OM Trac: https://trac.openmodelica.org/OpenModelica/ticket/6088

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1. Examples.ConvergenceTest.Ancillary_Saturation
   This goes into a branch of an if-else that I thought is unreachable (this should also not happen)??? After updating the assert message, it is seen that h=nan

2. Examples.ConvergenceTest.setSat
   An iteration written by me does not converge, close to the critical point, but it works in Dymola. There is a warning about abs value being negative.

3. Examples.MediaTestModels.IsopentaneTestModel (during initialization)
   Failing assert

4. Examples.Validation.Derivatives_SaturationBoundary (during initialization)
   fails during initialization, with liq.s and vap.s having same value

5. Examples.Validation.idealGasLimit
   this should converge to a certain value, but starts to oscillate because of numerical noise, also with other tools, but at a later point. Might be solved by changing some tolerance or other setting?

[thorade]

Number 3 Isopentane is now also simulating, started to work with
https://libraries.openmodelica.org/branches/history/newInst/2020-11-09%2011:30:51..2020-11-09%2020:32:27.html
OpenModelica/OpenModelica#6877

[thorade]

Division by zero check: OpenModelica/OpenModelica#7023

[thorade]

OM master switched to newInst on 2020-12-14:
https://libraries.openmodelica.org/branches/history/master/00_history.html
https://libraries.openmodelica.org/branches/history/master/2020-12-14%2003:04:35..2020-12-14%2022:49:53.html

master Library report, Library coverage, last 7 runs

newInst Library report, Library coverage, last 7 runs

[thorade]

• https://libraries.openmodelica.org/branches/history/master/2021-01-12%2022:58:17..2021-01-14%2001:15:22.html
• https://libraries.openmodelica.org/branches/history/master/2021-01-14%2001:15:22..2021-01-15%2000:56:20.html

[thorade]

Some models broken due to #45, will be addressed through #33

[bilderbuchi]

With the fix for #48, we are now at 36/41 models simulating: https://libraries.openmodelica.org/branches/master/HelmholtzMedia/HelmholtzMedia.html

A fresh case not yet mentioned is Examples.ConvergenceTest.SinglePhase_setState_pramp_Tsine , which tells about setSat_p not converging.

[bilderbuchi]

Examples.Validation.idealGasLimit
this should converge to a certain value, but starts to oscillate because of numerical noise, also with other tools, but at a later point. Might be solved by changing some tolerance or other setting?

Some of the problems stem from density being prescribed to go below its lower limit (Modelica.Constants.small). I guess something like

  when d < 2*Modelica.Constants.small then
    terminate("Stopping before hitting the density limit");
  end when;

could help with that at least.

[thorade]

I have change the stop time of that example in 224effc

[thorade]

also see #40 for the convergence criterion

[thorade]

It would be interesting to see where this NaN during initialization is coming from:
https://libraries.openmodelica.org/branches/master/HelmholtzMedia/files/HelmholtzMedia_HelmholtzMedia.Examples.Validation.Derivatives_SaturationBoundary.sim