modelPartialOneWayFlowElement

Partial model for flow resistance with one-way flow

Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface, Buildings.Airflow.Multizone.BaseClasses.ErrorControl.

Information

This partial model is used to model one way flow-elements. It holds the conservation equations and should be extended by definition of one of the following variables:

m_flow = mass flow rate trough the component

V_flow = volume flow rate through the component

The flow from A->B is the positive flow. The resulting equation should be in the extends statement, not in the equation section since this model sets both m_flow = V_flow*rho and V_flow = m_flow/rho.

Parameters

Type	Name	Default	Description
Advanced
Boolean	homotopyInitialization	true	= true, use homotopy method
Boolean	useDefaultProperties	true	Set to false to use density and viscosity based on actual medium state, rather than using default values
Modelica.Units.SI.PressureDifference	dp_turbulent	0.1	Pressure difference where laminar and turbulent flow relation coincide. Recommended = 0.1

Components

Type	Name	Default	Description
Modelica.Units.SI.VolumeFlowRate	V_flow	m_flow/rho	Volume flow rate through the component
Modelica.Units.SI.Density	rho		Fluid density at port_a

Revisions

September 22, 2025, by Michael Wetter:
Set unbounded=true for mExc_flow. This is to have the same implementation as in Buildings.Airflow.Multizone.BaseClasses.TwoWayFlowElement where this change was done to avoid spikes in port_a.m_flow in Buildings.Airflow.Multizone.Examples.OneOpenDoor.
This is for Buildings, #4360.
September 19, 2025, by Michael Wetter:
Introduced protected parameter sqrt_dp_turbulent, which is needed to improve computing efficiency if flow exponent is 0.5.
This is for IBPSA, #2043.
February 2, 2022, by Michael Wetter:
Revised implementation.
This is for IBPSA, #1436.
Apr 06, 2021, by Klaas De Jonge:
First implementation.