functionpowerLaw_m_flow_der
1st derivative of function that computes pressure drop for given mass flow rate
Extends from Modelica.Icons.Function (Icon for functions).
Information
Function that implements the first order derivative of
Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow
with respect to the mass flow rate m_flow,
assuming constant flow coefficients.
When called with m_flow_der=der(m_flow), this function returns
the time derivative of dp.
When called with m_flow_der=1, this function returns
the derivative of dp with respect to m_flow.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.MassFlowRate | m_flow | Mass flow rate | |
| Real | k | Flow coefficient, k = m_flow/ dp^(1/n) | |
| Real | n | Flow exponent, n=1 for laminar, n=2 for turbulent | |
| Modelica.Units.SI.MassFlowRate | m_flow_turbulent | Mass flow rate where transition to turbulent flow occurs | |
| Modelica.Units.SI.PressureDifference | dp_turbulent | Pressure difference where turbulent flow occurs | |
| Real | m | Flow exponent for the pressure drop | |
| Real | a1 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | a3 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | a5 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | C | Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n) | |
| Real | b1 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | b3 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | b5 | Polynomial coefficient for regularized implementation of flow resistance | |
| Real | m_flow_der | Derivative of mass flow rate in design flow direction |
Outputs
| Type | Name | Default | Description |
|---|---|---|---|
| Real | dp_der | Derivative of pressure difference |
Revisions
-
May 30, 2026, by Michael Wetter:
First implementation.
This is for Buildings, #4620.