Buildings.Fluid.BaseClasses.FlowModels.Validation

Collection of validation models

Information

This package contains validation models for the classes in Buildings.Fluid.BaseClasses.FlowModels.

Note that most validation models contain simple input data which may not be realistic, but for which the correct output can be obtained through an analytic solution. The examples plot various outputs, which have been verified against these solutions. These model outputs are stored as reference data and used for continuous validation whenever models in the library change.

Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).

Package Content

Name	Description
BasicFlowFunction_dp_DerivativeCheck	Model that checks the correct implementation of the 1st order derivative of the flow function
BasicFlowFunction_dp_DerivativeCheck2	Model that checks the correct implementation of the 2nd order derivative of the flow function
BasicFlowFunction_m_flow_DerivativeCheck	Model that checks the correct implementation of the 1st order derivative of the flow function
BasicFlowFunction_m_flow_DerivativeCheck2	Model that checks the correct implementation of the 2nd order derivative of the flow function
InverseFlowFunctions	Test model for flow function and its inverse
InversePowerLaws	Test model for power law flow function and its inverse
InvertingBasicFlowFunction_dp	Test model that inverts basicFlowFunction_dp
InvertingBasicFlowFunction_m_flow	Test model that inverts basicFlowFunction_m_flow
InvertingPowerLaw_dp	Test model that inverts powerLaw_dp
InvertingPowerLaw_m_flow	Test model that inverts powerLaw_m_flow
PowerLaw_dp	Test model for power law function
PowerLaw_dp_DerivativeCheck	Model that checks the correct implementation of the 1st order derivative of the power law function
PowerLaw_dp_DerivativeCheck2	Model that checks the correct implementation of the 2nd order derivative of the power law function
PowerLaw_m_flow_DerivativeCheck	Model that checks the correct implementation of the 1st order derivative of the power law function
PowerLaw_m_flow_DerivativeCheck2	Model that checks the correct implementation of the 2nd order derivative of the power law function

Buildings.Fluid.BaseClasses.FlowModels.Validation.BasicFlowFunction_dp_DerivativeCheck

Model that checks the correct implementation of the 1st order derivative of the flow function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp and its first order derivative Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp_der. If the derivative implementation is wrong, the simulation will stop with an error.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.35	Flow coefficient
MassFlowRate	m_flow_turbulent	0.36	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model BasicFlowFunction_dp_DerivativeCheck "Model that checks the correct implementation of the 1st order derivative of the flow function" extends Modelica.Icons.Example; constant Real gain = 2 "Gain for computing the mass flow rate"; parameter Real k = 0.35 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent=0.36 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow_comp "Comparison value for m_flow"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.MassFlowRate err "Integration error"; initial equation m_flow = m_flow_comp; equation dp = time*gain; m_flow = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp( dp=dp, k = k, m_flow_turbulent=m_flow_turbulent); der(m_flow) = der(m_flow_comp); err = m_flow-m_flow_comp; assert(abs(err) < 1E-3, "Error in implementation."); end BasicFlowFunction_dp_DerivativeCheck;

Buildings.Fluid.BaseClasses.FlowModels.Validation.BasicFlowFunction_dp_DerivativeCheck2

Model that checks the correct implementation of the 2nd order derivative of the flow function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp and its second order derivative Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp_der2. If the derivative implementation is wrong, the simulation will stop with an error.

Implementation

The pressure drop dp is increased non-linearly in order for the first and second derivatives in Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp_der2 to be non-zero during part of the simulation. This will ensure full code coverage of this function.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.35	Flow coefficient
MassFlowRate	m_flow_turbulent	0.36	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model BasicFlowFunction_dp_DerivativeCheck2 "Model that checks the correct implementation of the 2nd order derivative of the flow function" extends Modelica.Icons.Example; parameter Real k = 0.35 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent=0.36 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow_comp "Comparison value for m_flow"; Real der_m_flow(unit="kg/s2") "1st order derivative of mass flow rate"; Real der_m_flow_comp(unit="kg/s2") "2nd order derivative of comparison value for m_flow"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.MassFlowRate err_m_flow "Integration error for m_flow"; Real err_der_m_flow(unit="kg/s2") "Integration error for der_m_flow"; initial equation m_flow = m_flow_comp; der_m_flow = der_m_flow_comp; equation // Multiply by 1 to avoid a warning due to unit mismatch, // and raise to third power so that dp_der2 has positive and negative sign // in Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp_der2 dp = 1*time^3; m_flow = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp( dp=dp, k = k, m_flow_turbulent=m_flow_turbulent); // Equate first and second order derivatives der_m_flow = der(m_flow); der_m_flow_comp = der(m_flow_comp); der(der_m_flow) = der(der_m_flow_comp); // Error control err_m_flow = m_flow-m_flow_comp; assert(abs(err_m_flow) < 1E-3, "Error in implementation."); err_der_m_flow = der_m_flow-der_m_flow_comp; assert(abs(err_der_m_flow) < 1E-3, "Error in implementation."); end BasicFlowFunction_dp_DerivativeCheck2;

Buildings.Fluid.BaseClasses.FlowModels.Validation.BasicFlowFunction_m_flow_DerivativeCheck

Model that checks the correct implementation of the 1st order derivative of the flow function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow and its first order derivative Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow_der. If the derivative implementation is wrong, the simulation will stop with an error.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.35	Flow coefficient
MassFlowRate	m_flow_turbulent	0.36	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model BasicFlowFunction_m_flow_DerivativeCheck "Model that checks the correct implementation of the 1st order derivative of the flow function" extends Modelica.Icons.Example; constant Real gain = 0.5 "Gain for computing the mass flow rate"; parameter Real k = 0.35 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent=0.36 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.PressureDifference dp_comp "Comparison value for dp"; Modelica.Units.SI.PressureDifference err "Integration error"; initial equation dp = dp_comp; equation m_flow = time*gain; dp = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow( m_flow=m_flow, k = k, m_flow_turbulent=m_flow_turbulent); der(dp) = der(dp_comp); err = dp-dp_comp; assert(abs(err) < 1E-3, "Error in implementation."); end BasicFlowFunction_m_flow_DerivativeCheck;

Buildings.Fluid.BaseClasses.FlowModels.Validation.BasicFlowFunction_m_flow_DerivativeCheck2

Model that checks the correct implementation of the 2nd order derivative of the flow function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow and its second order derivative Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow_der2. If the derivative implementation is wrong, the simulation will stop with an error.

Implementation

The mass flow rate m_flow is increased non-linearly in order for the first and second derivatives in Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow_der2 to be non-zero during part of the simulation. This will ensure full code coverage of this function.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.35	Flow coefficient
MassFlowRate	m_flow_turbulent	0.36	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model BasicFlowFunction_m_flow_DerivativeCheck2 "Model that checks the correct implementation of the 2nd order derivative of the flow function" extends Modelica.Icons.Example; Buildings.Utilities.Diagnostics.CheckEquality cheEqu1( threShold=1e-3) "Block for checking integration error"; Buildings.Utilities.Diagnostics.CheckEquality cheEqu2( threShold=1e-3) "Block for checking integration error"; parameter Real k = 0.35 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent=0.36 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.PressureDifference dp_comp "Comparison value for dp"; Real der_dp(unit="Pa/s") "1st order derivative of pressure drop"; Real der_dp_comp(unit="Pa/s") "2nd order derivative of comparison value for pressure drop"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference err_dp "Integration error for dp"; Real err_der_dp(unit="Pa/s") "Integration error for der_dp"; initial equation dp = dp_comp; der_dp = der_dp_comp; equation // Divide by 8 to avoid a warning due to unit mismatch, and // and raise to third power so that m_flow_der2 has positive and negative sign // in Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow_der2 m_flow = time^3/8; dp = Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow( m_flow=m_flow, k = k, m_flow_turbulent=m_flow_turbulent); // Equate first and second order derivatives der_dp = der(dp); der_dp_comp = der(dp_comp); der(der_dp) = der(der_dp_comp); // Error control cheEqu1.u1 = dp; cheEqu1.u2 = dp_comp; err_dp = cheEqu1.y; assert(abs(err_dp) < 1E-3, "Error in implementation."); cheEqu2.u1 = der_dp; cheEqu2.u2 = der_dp_comp; err_der_dp = cheEqu2.y; assert(abs(err_der_dp) < 1E-3, "Error in implementation."); end BasicFlowFunction_m_flow_DerivativeCheck2;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InverseFlowFunctions

Test model for flow function and its inverse

Information

This model tests the inverse formulation of the flow functions. The pressure difference dp and dpCalc need to be equal up to the solver tolerance, except for a small neighborhood around the origin. In this neighborhood around the origin, the functions Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp and Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow do not have an analytic expression for their inverse function and hence the implementation of the inverse function slightly differs.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5
MassFlowRate	m_flow_nominal	1	Nominal flow rate [kg/s]

Modelica definition

model InverseFlowFunctions "Test model for flow function and its inverse" extends Modelica.Icons.Example; Modelica.Units.SI.MassFlowRate m_flow; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa") "Pressure difference"; Modelica.Units.SI.PressureDifference dpCalc(displayUnit="Pa") "Pressure difference computed by the flow functions"; Modelica.Units.SI.Pressure deltaDp(displayUnit="Pa") "Pressure difference between input and output to the functions"; Modelica.Units.SI.Time dTime=2; parameter Real k = 0.5; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1 "Nominal flow rate"; equation dp = (time-0.5)/dTime * 20; m_flow=FlowModels.basicFlowFunction_dp(dp=dp, k=k, m_flow_turbulent=m_flow_nominal*0.3); dpCalc=FlowModels.basicFlowFunction_m_flow(m_flow=m_flow, k=k, m_flow_turbulent=m_flow_nominal*0.3); deltaDp = dp - dpCalc; end InverseFlowFunctions;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InversePowerLaws

Test model for power law flow function and its inverse

Information

This model tests the inverse formulation of the power law flow functions for three values of the flow exponent: n=1 (laminar flow), n=1.25, and n=2 (turbulent flow).

The pressure difference dp and dpCalc need to be equal up to the solver tolerance, except for a small neighborhood around the origin. In this neighborhood around the origin, the functions Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp and Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow do not have an analytic expression for their inverse function and hence the implementation of the inverse function slightly differs.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5
Real	n[3]	{1,1/0.8,2}	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_nominal	1	Nominal flow rate [kg/s]
MassFlowRate	m_flow_turbulent	m_flow_nominal*0.3	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model InversePowerLaws "Test model for power law flow function and its inverse" extends Modelica.Icons.Example; parameter Real k = 0.5; parameter Real n[3](each min=1, each max=2) = {1, 1/0.8, 2} "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1 "Nominal flow rate"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent=m_flow_nominal*0.3 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow[3]; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa") "Pressure difference"; Modelica.Units.SI.PressureDifference dpCalc[3](each displayUnit="Pa") "Pressure difference computed by the flow functions"; Modelica.Units.SI.Pressure deltaDp[3](each displayUnit="Pa") "Pressure difference between input and output to the functions"; Modelica.Units.SI.Time dTime=2; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent[3]( each displayUnit="Pa", each fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m[3](each fixed=false) "Flow exponent for the pressure drop"; parameter Real a1[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C[3](each fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5[3](each fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation for i in 1:3 loop (dp_turbulent[i], m[i], a1[i], a3[i], a5[i], C[i], b1[i], b3[i], b5[i]) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n[i], m_flow_turbulent=m_flow_turbulent); end for; equation dp = (time-0.5)/dTime * 20; for i in 1:3 loop m_flow[i]=FlowModels.powerLaw_dp( dp=dp, k=k, n=n[i], m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent[i], m=m[i], a1=a1[i], a3=a3[i], a5=a5[i], C=C[i], b1=b1[i], b3=b3[i], b5=b5[i]); dpCalc[i]=FlowModels.powerLaw_m_flow( m_flow=m_flow[i], k=k, n=n[i], m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent[i], m=m[i], a1=a1[i], a3=a3[i], a5=a5[i], C=C[i], b1=b1[i], b3=b3[i], b5=b5[i]); deltaDp[i] = dp - dpCalc[i]; end for; end InversePowerLaws;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InvertingBasicFlowFunction_dp

Test model that inverts basicFlowFunction_dp

Information

This model tests whether the Modelica translator substitutes the inverse function for Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp. Specifically, this function declares in its annotation section that its inverse is provided by Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow. Translating this model should therefore give no nonlinear equations after the symbolic manipulation.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient
MassFlowRate	m_flow_nominal	1.5	Nominal mass flow rate [kg/s]

Modelica definition

model InvertingBasicFlowFunction_dp "Test model that inverts basicFlowFunction_dp" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1.5 "Nominal mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa", start=0) "Pressure difference"; equation m_flow = 4*(time-0.5); m_flow = FlowModels.basicFlowFunction_dp(dp=dp, k=k, m_flow_turbulent=m_flow_nominal*0.3); end InvertingBasicFlowFunction_dp;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InvertingBasicFlowFunction_m_flow

Test model that inverts basicFlowFunction_m_flow

Information

This model tests whether the Modelica translator substitutes the inverse function for Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow. Specifically, this function declares in its annotation section that its inverse is provided by Buildings.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp. Translating this model should therefore give no nonlinear equations after the symbolic manipulation.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient
MassFlowRate	m_flow_nominal	0.5	Nominal mass flow rate [kg/s]

Modelica definition

model InvertingBasicFlowFunction_m_flow "Test model that inverts basicFlowFunction_m_flow" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=0.5 "Nominal mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow(start=0) "Mass flow rate"; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa") "Pressure difference"; equation dp = 4*(time-0.5); dp = FlowModels.basicFlowFunction_m_flow(m_flow=m_flow, k=k, m_flow_turbulent=m_flow_nominal*0.3); end InvertingBasicFlowFunction_m_flow;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InvertingPowerLaw_dp

Test model that inverts powerLaw_dp

Information

This model tests whether the Modelica translator substitutes the inverse function for Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp. Specifically, this function declares in its annotation section that its inverse is provided by Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow. Translating this model should therefore give no nonlinear equations after the symbolic manipulation.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_nominal	1.5	Nominal mass flow rate [kg/s]
MassFlowRate	m_flow_turbulent	m_flow_nominal*0.3	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model InvertingPowerLaw_dp "Test model that inverts powerLaw_dp" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=1.5 "Nominal mass flow rate"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent(min=0)= m_flow_nominal*0.3 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa", start=0) "Pressure difference"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); equation m_flow = 4*(time-0.5); m_flow = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp( dp=dp, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); end InvertingPowerLaw_dp;

Buildings.Fluid.BaseClasses.FlowModels.Validation.InvertingPowerLaw_m_flow

Test model that inverts powerLaw_m_flow

Information

This model tests whether the Modelica translator substitutes the inverse function for Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow. Specifically, this function declares in its annotation section that its inverse is provided by Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp. Translating this model should therefore give no nonlinear equations after the symbolic manipulation.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_nominal	0.5	Nominal mass flow rate [kg/s]
MassFlowRate	m_flow_turbulent	m_flow_nominal*0.3	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model InvertingPowerLaw_m_flow "Test model that inverts powerLaw_m_flow" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal=0.5 "Nominal mass flow rate"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent(min=0)= m_flow_nominal*0.3 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow(start=0) "Mass flow rate"; Modelica.Units.SI.PressureDifference dp(displayUnit="Pa") "Pressure difference"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); equation dp = 4*(time-0.5); dp = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow( m_flow=m_flow, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); end InvertingPowerLaw_m_flow;

Buildings.Fluid.BaseClasses.FlowModels.Validation.PowerLaw_dp

Test model for power law function

Information

This example compares the mass flow rate of Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp by comparing it with the mass flow rate from Buildings.Airflow.Multizone.BaseClasses.powerLawFixedM. Outside the turbulent region, the two models give the same result. However, inside the turbulent region, the results differ slightly because Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp uses a 5th order polynomial to ensure C2 continuity, while Buildings.Airflow.Multizone.BaseClasses.powerLawFixedM uses a 7th order polynomial.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	gamma	1.5	Normalized flow rate where dphi(0)/dpi intersects phi(1)
Real	a	gamma	Polynomial coefficient for regularized implementation of flow resistance
Real	b	1/8m^2 - 3gamma - 3/2*m + ...	Polynomial coefficient for regularized implementation of flow resistance
Real	c	-1/4m^2 + 3gamma + 5/2*m -...	Polynomial coefficient for regularized implementation of flow resistance
Real	d	1/8*m^2 - gamma - m + 15.0/8	Polynomial coefficient for regularized implementation of flow resistance
Density	rho	1.2	Fluid density [kg/m3]
MassFlowRate	m_flow_nominal	5	Nominal mass flow rate used to compute the flow coefficient k and C for the power law model [kg/s]
PressureDifference	dp_nominal	10	Nominal pressure difference used to compute the flow coefficient k and C for the power law model [Pa]
Real	n	1/0.8	Flow exponent, n=1 for laminar, n=2 for turbulent
Real	k	m_flow_nominal/dp_nominal^(1...	Flow coefficient, k = m_flow/ dp^(1/n)
MassFlowRate	m_flow_turbulent	m_flow_nominal	Mass flow rate where regularization starts, here set to the same value as m_flow_nominal [kg/s]

Modelica definition

model PowerLaw_dp "Test model for power law function" extends Modelica.Icons.Example; parameter Real gamma(min=1) = 1.5 "Normalized flow rate where dphi(0)/dpi intersects phi(1)"; parameter Real a = gamma "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b = 1/8*m^2 - 3*gamma - 3/2*m + 35.0/8 "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real c = -1/4*m^2 + 3*gamma + 5/2*m - 21.0/4 "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real d = 1/8*m^2 - gamma - m + 15.0/8 "Polynomial coefficient for regularized implementation of flow resistance"; parameter Modelica.Units.SI.Density rho = 1.2 "Fluid density"; parameter Modelica.Units.SI.MassFlowRate m_flow_nominal = 5 "Nominal mass flow rate used to compute the flow coefficient k and C for the power law model"; parameter Modelica.Units.SI.PressureDifference dp_nominal(displayUnit="Pa") = 10 "Nominal pressure difference used to compute the flow coefficient k and C for the power law model"; parameter Real n(min=1, max=2) = 1/0.8 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Real k = m_flow_nominal/dp_nominal^(1/n) "Flow coefficient, k = m_flow/ dp^(1/n)"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent(min=0) = m_flow_nominal "Mass flow rate where regularization starts, here set to the same value as m_flow_nominal"; Modelica.Units.SI.PressureDifference dp "Pressure difference"; Modelica.Units.SI.VolumeFlowRate V_flow "Volume flow rate computed with model powerLawFixedM that uses C"; Modelica.Units.SI.MassFlowRate m2_flow "Mass flow rate computed based on V_flow to compare equality with m_flow"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate computed with model powerLawFixedM that uses k"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); equation dp = 20*(-1+2*time); V_flow = Buildings.Airflow.Multizone.BaseClasses.powerLawFixedM( C=m_flow_nominal/rho/dp_nominal^m, a=a, b=b, c=c, d=d, dp=dp, m=m, dp_turbulent=dp_turbulent); m2_flow = V_flow * rho; m_flow = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp( dp=dp, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); end PowerLaw_dp;

Buildings.Fluid.BaseClasses.FlowModels.Validation.PowerLaw_dp_DerivativeCheck

Model that checks the correct implementation of the 1st order derivative of the power law function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp and its first order derivative Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp_der. If the derivative implementation is wrong, the simulation will stop with an error.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient, k = m_flow/ dp^(1/n)
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_turbulent	0.1	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model PowerLaw_dp_DerivativeCheck "Model that checks the correct implementation of the 1st order derivative of the power law function" extends Modelica.Icons.Example; constant Real gain = 2 "Gain for computing the pressure difference"; parameter Real k = 0.5 "Flow coefficient, k = m_flow/ dp^(1/n)"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent = 0.1 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow_comp "Comparison value for m_flow"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.MassFlowRate err "Integration error"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); m_flow = m_flow_comp; equation dp = time*gain; m_flow = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp( dp=dp, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); der(m_flow) = der(m_flow_comp); err = m_flow-m_flow_comp; assert(abs(err) < 1E-3, "Error in implementation."); end PowerLaw_dp_DerivativeCheck;

Buildings.Fluid.BaseClasses.FlowModels.Validation.PowerLaw_dp_DerivativeCheck2

Model that checks the correct implementation of the 2nd order derivative of the power law function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp and its second order derivative Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp_der2. If the derivative implementation is wrong, the simulation will stop with an error.

Implementation

The pressure drop dp is increased non-linearly in order for the first and second derivatives in Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp_der2 to be non-zero during part of the simulation. This will ensure full code coverage of this function.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient, k = m_flow/ dp^(1/n)
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_turbulent	0.1	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model PowerLaw_dp_DerivativeCheck2 "Model that checks the correct implementation of the 2nd order derivative of the power law function" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient, k = m_flow/ dp^(1/n)"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent = 0.1 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.MassFlowRate m_flow_comp "Comparison value for m_flow"; Real der_m_flow(unit="kg/s2") "1st order derivative of mass flow rate"; Real der_m_flow_comp(unit="kg/s2") "1st order derivative of comparison value for m_flow"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.MassFlowRate err_m_flow "Integration error for m_flow"; Real err_der_m_flow(unit="kg/s2") "Integration error for der_m_flow"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); m_flow = m_flow_comp; der_m_flow = der_m_flow_comp; equation // Multiply by 1 to avoid a warning due to unit mismatch, // and raise to third power so that dp_der2 has positive and negative sign // in Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp_der2 dp = 1*time^3; m_flow = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_dp( dp=dp, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); // Equate first and second order derivatives der_m_flow = der(m_flow); der_m_flow_comp = der(m_flow_comp); der(der_m_flow) = der(der_m_flow_comp); // Error control err_m_flow = m_flow-m_flow_comp; assert(abs(err_m_flow) < 1E-3, "Error in implementation."); err_der_m_flow = der_m_flow-der_m_flow_comp; assert(abs(err_der_m_flow) < 1E-3, "Error in implementation."); end PowerLaw_dp_DerivativeCheck2;

Buildings.Fluid.BaseClasses.FlowModels.Validation.PowerLaw_m_flow_DerivativeCheck

Model that checks the correct implementation of the 1st order derivative of the power law function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow and its first order derivative Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow_der. If the derivative implementation is wrong, the simulation will stop with an error.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient, k = m_flow/ dp^(1/n)
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_turbulent	0.1	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model PowerLaw_m_flow_DerivativeCheck "Model that checks the correct implementation of the 1st order derivative of the power law function" extends Modelica.Icons.Example; constant Real gain = 0.5 "Gain for computing the mass flow rate"; parameter Real k = 0.5 "Flow coefficient, k = m_flow/ dp^(1/n)"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent = 0.1 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.PressureDifference dp_comp "Comparison value for dp"; Modelica.Units.SI.PressureDifference err "Integration error"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); dp = dp_comp; equation m_flow = time*gain; dp = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow( m_flow=m_flow, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); der(dp) = der(dp_comp); err = dp-dp_comp; assert(abs(err) < 1E-3, "Error in implementation."); end PowerLaw_m_flow_DerivativeCheck;

Buildings.Fluid.BaseClasses.FlowModels.Validation.PowerLaw_m_flow_DerivativeCheck2

Model that checks the correct implementation of the 2nd order derivative of the power law function

Information

This model validates the implementation of Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow and its second order derivative Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow_der2. If the derivative implementation is wrong, the simulation will stop with an error.

Implementation

The mass flow rate m_flow is increased non-linearly in order for the first and second derivatives in Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow_der2 to be non-zero during part of the simulation. This will ensure full code coverage of this function.

Extends from Modelica.Icons.Example (Icon for runnable examples).

Parameters

Type	Name	Default	Description
Real	k	0.5	Flow coefficient, k = m_flow/ dp^(1/n)
Real	n	1.5	Flow exponent, n=1 for laminar, n=2 for turbulent
MassFlowRate	m_flow_turbulent	0.1	Mass flow rate where transition to turbulent flow occurs [kg/s]

Modelica definition

model PowerLaw_m_flow_DerivativeCheck2 "Model that checks the correct implementation of the 2nd order derivative of the power law function" extends Modelica.Icons.Example; parameter Real k = 0.5 "Flow coefficient, k = m_flow/ dp^(1/n)"; parameter Real n(min=1, max=2) = 1.5 "Flow exponent, n=1 for laminar, n=2 for turbulent"; parameter Modelica.Units.SI.MassFlowRate m_flow_turbulent = 0.1 "Mass flow rate where transition to turbulent flow occurs"; Modelica.Units.SI.MassFlowRate m_flow "Mass flow rate"; Modelica.Units.SI.PressureDifference dp "Pressure drop"; Modelica.Units.SI.PressureDifference dp_comp "Comparison value for dp"; Real der_dp(unit="Pa/s") "1st order derivative of pressure drop"; Real der_dp_comp(unit="Pa/s") "1st order derivative of comparison value for pressure drop"; Modelica.Units.SI.PressureDifference err_dp "Integration error for dp"; Real err_der_dp(unit="Pa/s") "Integration error for der_dp"; protected parameter Modelica.Units.SI.PressureDifference dp_turbulent( displayUnit="Pa", fixed=false) "Pressure difference where turbulent flow occurs"; parameter Real m(fixed=false) "Flow exponent for the pressure drop"; parameter Real a1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real a5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real C(fixed=false) "Coefficient 1/k^n, based on the definition k = m_flow / dp^(1/n)"; parameter Real b1(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b3(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; parameter Real b5(fixed=false) "Polynomial coefficient for regularized implementation of flow resistance"; initial equation (dp_turbulent, m, a1, a3, a5, C, b1, b3, b5) = Buildings.Fluid.BaseClasses.FlowModels.powerLawData( k=k, n=n, m_flow_turbulent=m_flow_turbulent); dp = dp_comp; der_dp = der_dp_comp; equation // Divide by 8 to avoid a warning due to unit mismatch, and // and raise to third power so that m_flow_der2 has positive and negative sign // in Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow_der2 m_flow = time^3/8; dp = Buildings.Fluid.BaseClasses.FlowModels.powerLaw_m_flow( m_flow=m_flow, k=k, n=n, m_flow_turbulent=m_flow_turbulent, dp_turbulent=dp_turbulent, m=m, a1=a1, a3=a3, a5=a5, C=C, b1=b1, b3=b3, b5=b5); // Equate first and second order derivatives der_dp = der(dp); der_dp_comp = der(dp_comp); der(der_dp) = der(der_dp_comp); // Error control err_dp = dp-dp_comp; assert(abs(err_dp) < 1E-3, "Error in implementation."); err_der_dp = der_dp-der_dp_comp; assert(abs(err_der_dp) < 1E-3, "Error in implementation."); end PowerLaw_m_flow_DerivativeCheck2;