Version 4.14

Hydraulics Library 4.14 is part of Modelon’s 2020.2 release.

New versions of Modelon libraries are sold and distributed directly from Modelon, as well as approved resellers. 

Build 1 (2020-09-18)


This new version of the Modelon Hydraulics library comes with two main features:

  1. The first one is mostly visual: the new port icons highlight the presence of volume or not inside the associated component.
  2. The second one is in the physics modeled: oil cavitation is now properly modeled in volumes - until the liquid becomes entirely gaseous.


  • The interfaces have been reworked in order to better highlight the expected connections to each port. This affects every hydraulic component.
    • Three port types are now available:
      1. The flow port should be connected to volume ports only for efficient modeling.
      2. There should be one and only one volume port per node for efficient modeling.
      3. The neutral port is less constrained in terms of connection but some local rules might apply and would be detailed in components' help.
    • There is no more visual distinction on the port icon between what was a port_A and port_B previously, as this was reported to be more confusing than helpful. In two ports components, an arrow is added to highlight the positive direction of the flow.
    • Port icons have been adapted to fit the visual aspect of other Modelon libraries.
    • Previous Port_A and Port_B are now deprecated
  • Cavitation of the fluid is now properly modeled in VolumeDynamics. This includes:
    • when reaching vapour pressure, the oil starts to become gaseous,
    • the fraction of gaseous oil is tracked and oil pressure cannot raise (with incoming flow) unless the entire gaseous oil volume is transformed back into liquid oil.
    • The gaseous fraction of the oil volume is local to the volume and not transferred through ports. Mass flow exiting the volume is always liquid oil.
    • Warnings are raised if the entire volume of oil becomes gaseous, as the physics would not be ensured.
  • A single acting cylinder with feedback spring is added to the library.
  • Command logic now have a minimum value of the flow and an outflow enthalpy set to zero, as well as state selection avoided. This simplify mixing computations in case of non-optimal port connection.
  • Visualizers now have state selection set to avoid for pressure variables.

Fixed issues

  • Resolved array size mismatch in TwoPortFlexible, SpoolGeneric_4_X_X, DCV_4_2_X and DCV_4_3_X.
  • Updated PilotCheckValveCircuit to use an elastic friction model for better robustness
  • Propagated initialization parameters related to volumes in several components, especially in the DirectionalControl and Valves packages access these more conveniently.
  • Restrictions in Plunger and Differential cylinders were connected so that an external leakage from the chambers to the environment would be negative. For convenience only, these restrictions have been flipped to have a positive leakage flow when going from the chambers to the environment.

Build 2 (2020-11-02)

Fixed issues

  • Animation rendering issue of the single acting cylinder has been fixed.
  • Fixed working of connection warnings in flow port and volume port.

New classes

  • Hydraulics.Interfaces.FlowPort
  • Hydraulics.Interfaces.VolumePort
  • Hydraulics.Interfaces.NeutralPort
  • Hydraulics.Lines.Basic.Templates.TwoPort
  • Hydraulics.Cylinders.SingleActingCylinder
  • Hydraulics.Cylinders.Templates.SingleActingCylinder
  • Hydraulics.Cylinders.Interfaces.SingleActingCylinder

Moved classes

  • Hydraulics.RotaryActuators.ConstantFlowPump --> Hydraulics.Examples.PowerSteering.Components.ConstantFlowPump

Obsolete classes

Obsolete classes are placed in the package Utilities.Deprecated and will be removed after a year from the release when they were put in the deprecated package.

  • Hydraulics.Utilities.Deprecated.Port_A
  • Hydraulics.Utilities.Deprecated.Port_B
  • Hydraulics.Utilities.Deprecated.FourPort

Build 3 (2020-12-14)

Fixed Issues

  • Corrected usage of the non-existing parameter used in parameter enable annotation.