BuildingSystems.Fluid.BaseClasses.PartialThreeWayResistance

# .BuildingSystems.Fluid.BaseClasses.PartialThreeWayResistance

Flow splitter with partial resistance model at each port

## Information

Partial model for flow resistances with three ports such as a flow mixer/splitter or a three way valve.

If `energyDynamics ≠ Modelica.Fluid.Types.Dynamics.SteadyState`, then at the junction of the three flows, a mixing volume will be present. This will introduce a dynamic energy and momentum balance, which often breaks algebraic loops. The time constant of the mixing volume is determined by the parameter `tau`.

## Revisions

- March 7, 2022, by Michael Wetter:
  Set `final massDynamics=energyDynamics`.
  This is for #1542.
- March 22, 2020, by Filip Jorissen:
  Corrected error message of asserts that verify whether flow reversal occurs when `verifyFlowReversal=true` and `portFlowDirection<>Bidirectional`. See #1327.
- July 7, 2018, by Filip Jorissen:
  Added asserts that verify whether flow reversal occurs when `verifyFlowReversal=true` and `portFlowDirection<>Bidirectional`. See #963.
- July 8, 2018, by Filip Jorissen:
  Added nominal value of `h_outflow` in `FluidPorts`. See #977.
- March 30, 2018, by Filip Jorissen:
  Added graphical illustrations for the values of `portFlowDirection`. Added asserts that verify the consistency of the values of `portFlowDirection`. See #902.
- February 22, 2016, by Michael Wetter:
  Conditionally removed control volume `vol`, and added the conditional connnector `port_internal`. This was already done when the parameter `dynamicBalance` was present, but was updated wrong when this parameter was removed. Without these conditional components, the regression test for `BuildingSystems.Fluid.Examples.ResistanceVolumeFlowReversal` fails to simulate.
- December 17, 2015, by Michael Wetter:
  Added assignment `redeclare final package Medium=Medium` as this is required for OpenModelica. This is for https://github.com/lbl-srg/modelica-buildings/issues/475.
- February 20, 2016, by Ruben Baetens:
  Removal of `dynamicBalance` as parameter for `massDynamics` and `energyDynamics`.
- April 13 2015, by Filip Jorissen:
  Exposed options for flow reversal to users and added corresponding implementation.
- March 23 2010, by Michael Wetter:
  Changed start values from `system.p_start` or (code `T_start`) to `Medium.p_default`.
- September 18, 2008 by Michael Wetter:
  Replaced splitter model with a fluid port since the splitter model in Modelica.Fluid 1.0 beta does not transport `mC_flow`.
- June 11, 2008 by Michael Wetter:
  First implementation.

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