Buildings.Fluid.Movers.Examples
Collection of models that illustrate model use and test models
Information
This package contains examples for the use of models that can be found in Buildings.Fluid.Movers.
Extends from Modelica.Icons.ExamplesPackage (Icon for packages containing runnable examples).
Package Content
| Name | Description |
|---|---|
 ClosedLoop_y
|
Flow machine with feedback control |
| MoverContinuous
|
Example model of movers using a real input for setting the stage |
| MoverParameter
|
Example model of movers using a parameter for setting the stage |
| MoverStages
|
Example model of movers using an integer input for setting the stage |
| PumpsParallel
|
Two flow machines in parallel |
| PumpsSeries
|
Two flow machines in series |
| SpeedControlled_y_pumpCurves
|
Pumps that illustrates the use of the pump curves |
Buildings.Fluid.Movers.Examples.ClosedLoop_y
Flow machine with feedback control
Information
This example demonstrates the use of a fan with closed loop control. The fan is controlled to track a required mass flow rate.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 0.1 | Nominal mass flow rate [kg/s] |
| PressureDifference | dp_nominal | 500 | Nominal pressure difference [Pa] |
Modelica definition
model ClosedLoop_y "Flow machine with feedback control"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Air;
parameter Modelica.SIunits.MassFlowRate m_flow_nominal= 0.1
"Nominal mass flow rate";
parameter Modelica.SIunits.PressureDifference dp_nominal = 500
"Nominal pressure difference";
Modelica.Blocks.Sources.Pulse y(
offset=0.25,
startTime=0,
amplitude=0.5,
period=15*60) "Input signal";
Buildings.Fluid.Sources.Boundary_pT sou(
redeclare package Medium = Medium,
use_p_in=false,
p=101325,
T=293.15,
nPorts=2);
FixedResistances.PressureDrop dp1(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=dp_nominal/2) "Pressure drop";
Buildings.Fluid.FixedResistances.PressureDrop dp2(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=dp_nominal/2) "Pressure drop";
Buildings.Fluid.Movers.SpeedControlled_y fan(
redeclare package Medium = Medium,
per(pressure(V_flow={0,m_flow_nominal,2*m_flow_nominal}/1.2,
dp={2*dp_nominal,dp_nominal,0})),
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial) "Fan";
Buildings.Fluid.Sensors.MassFlowRate senMasFlo(redeclare package Medium =
Medium);
Buildings.Controls.Continuous.LimPID conPID(
Td=1,
k=0.5,
Ti=15);
Modelica.Blocks.Math.Gain gain1(k=1/m_flow_nominal);
equation
connect(sou.ports[1], senMasFlo.port_a);
connect(senMasFlo.port_b, dp1.port_a);
connect(dp1.port_b, fan.port_a);
connect(fan.port_b, dp2.port_a);
connect(dp2.port_b, sou.ports[2]);
connect(senMasFlo.m_flow, gain1.u);
connect(gain1.y, conPID.u_m);
connect(y.y, conPID.u_s);
connect(conPID.y, fan.y);
end ClosedLoop_y;
Buildings.Fluid.Movers.Examples.MoverContinuous
Example model of movers using a real input for setting the stage
Information
This example demonstrates the use of a RealInput
connector for a mover model.
Extends from MoverParameter (Example model of movers using a parameter for setting the stage).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 2 | Nominal mass flow rate [kg/s] |
| PressureDifference | dp_nominal | 10000 | Nominal pressure raise [Pa] |
Modelica definition
model MoverContinuous
"Example model of movers using a real input for setting the stage"
extends MoverParameter(
pump_Nrpm(inputType=Buildings.Fluid.Types.InputType.Continuous),
pump_m_flow(inputType=Buildings.Fluid.Types.InputType.Continuous),
pump_y(inputType=Buildings.Fluid.Types.InputType.Continuous),
pump_dp(inputType=Buildings.Fluid.Types.InputType.Continuous));
Modelica.Blocks.Sources.Ramp ramp(duration=1) "Ramp input for all movers";
Modelica.Blocks.Math.Gain gaiNrpm(k=2000) "Nominal rpm";
Modelica.Blocks.Math.Gain gai_m_flow(k=m_flow_nominal)
"Nominal mass flow rate";
Modelica.Blocks.Math.Gain gai_dp(k=dp_nominal) "Nominal pressure drop";
equation
connect(gaiNrpm.y, pump_Nrpm.Nrpm);
connect(gai_dp.y, pump_dp.dp_in);
connect(gai_m_flow.y, pump_m_flow.m_flow_in);
connect(gaiNrpm.u, ramp.y);
connect(gai_m_flow.u, ramp.y);
connect(gai_dp.u, ramp.y);
connect(pump_y.y, ramp.y);
end MoverContinuous;
Buildings.Fluid.Movers.Examples.MoverParameter
Example model of movers using a parameter for setting the stage
Information
This example demonstrates the use of a Parameter
set point for a mover model.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 2 | Nominal mass flow rate [kg/s] |
| PressureDifference | dp_nominal | 10000 | Nominal pressure raise [Pa] |
Modelica definition
model MoverParameter
"Example model of movers using a parameter for setting the stage"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water;
parameter Modelica.SIunits.MassFlowRate m_flow_nominal=2
"Nominal mass flow rate";
FlowControlled_m_flow pump_m_flow(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
use_inputFilter=false,
massFlowRates={0,0.5,1}*m_flow_nominal,
inputType=Buildings.Fluid.Types.InputType.Constant,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Pump with m_flow input";
Buildings.Fluid.Sources.Boundary_pT sou(
redeclare package Medium = Medium,
nPorts=4) "Fluid source";
Buildings.Fluid.Sources.Boundary_pT sin(redeclare package Medium = Medium,
nPorts=4) "Fluid sink";
SpeedControlled_y pump_y(
redeclare package Medium = Medium,
redeclare Buildings.Fluid.Movers.Data.Pumps.Wilo.Stratos25slash1to4 per(
speeds_rpm=1800*{0,0.5,1}, constantSpeed_rpm=1800),
use_inputFilter=false,
inputType=Buildings.Fluid.Types.InputType.Constant,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Pump with normalised speed input";
FlowControlled_dp pump_dp(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
redeclare Buildings.Fluid.Movers.Data.Pumps.Wilo.Stratos25slash1to4 per,
use_inputFilter=false,
heads={0,0.5,1}*dp_nominal,
inputType=Buildings.Fluid.Types.InputType.Constant,
dp_nominal=dp_nominal,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Pump with pressure head input";
FixedResistances.PressureDrop res(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=dp_nominal)
"Pressure drop component for avoiding singular system";
SpeedControlled_Nrpm pump_Nrpm(
redeclare package Medium = Medium,
use_inputFilter=false,
redeclare Buildings.Fluid.Movers.Data.Pumps.Wilo.Stratos25slash1to4 per(
speeds_rpm={0,1000,2000}, constantSpeed_rpm=2000),
inputType=Buildings.Fluid.Types.InputType.Constant,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Pump with speed input";
parameter Modelica.SIunits.PressureDifference dp_nominal=10000
"Nominal pressure raise";
equation
connect(sou.ports[1], pump_m_flow.port_a);
connect(pump_m_flow.port_b, sin.ports[1]);
connect(res.port_a, pump_dp.port_b);
connect(pump_y.port_b, sin.ports[2]);
connect(res.port_b, sin.ports[3]);
connect(pump_dp.port_a, sou.ports[2]);
connect(pump_y.port_a, sou.ports[3]);
connect(sou.ports[4], pump_Nrpm.port_a);
connect(pump_Nrpm.port_b, sin.ports[4]);
end MoverParameter;
Buildings.Fluid.Movers.Examples.MoverStages
Example model of movers using an integer input for setting the stage
Information
This example demonstrates the use of the Integer
stage connector for a mover model.
Note that integer input 1 refers to the first stage, whereas
input 0 switches the mover off.
Extends from Buildings.Fluid.Movers.Examples.MoverParameter (Example model of movers using a parameter for setting the stage).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 2 | Nominal mass flow rate [kg/s] |
| PressureDifference | dp_nominal | 10000 | Nominal pressure raise [Pa] |
Modelica definition
model MoverStages
"Example model of movers using an integer input for setting the stage"
extends Buildings.Fluid.Movers.Examples.MoverParameter(
pump_Nrpm(inputType=Buildings.Fluid.Types.InputType.Stages),
pump_m_flow(inputType=Buildings.Fluid.Types.InputType.Stages),
pump_y(inputType=Buildings.Fluid.Types.InputType.Stages),
pump_dp(inputType=Buildings.Fluid.Types.InputType.Stages));
package Medium = Buildings.Media.Water;
parameter Modelica.SIunits.MassFlowRate m_flow_nominal=2
"Nominal mass flow rate";
Modelica.Blocks.Sources.IntegerTable integerTable(table=[0,1; 0.3,2; 0.6,3])
"Integer step input, 1 is off, 2 is on";
parameter Modelica.SIunits.PressureDifference dp_nominal=10000 "Nominal pressure raise";
equation
connect(integerTable.y, pump_Nrpm.stage);
connect(integerTable.y, pump_m_flow.stage);
connect(integerTable.y, pump_y.stage);
connect(integerTable.y, pump_dp.stage);
end MoverStages;
Buildings.Fluid.Movers.Examples.PumpsParallel
Two flow machines in parallel
Information
This example tests the configuration of two flow machines that are installed in parallel. Both flow machines start with full speed. At t=150 second, the speed of the flow machine on the top is reduced to zero. As its speed is reduced, the mass flow rate changes its direction in such a way that the flow machine at the top has reverse flow.Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 1 | Nominal mass flow rate [kg/s] |
| Density | rho_nominal | 1000 | Density, used to compute fluid mass [kg/m3] |
Modelica definition
model PumpsParallel "Two flow machines in parallel"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water "Medium model";
parameter Modelica.SIunits.MassFlowRate m_flow_nominal= 1
"Nominal mass flow rate";
parameter Modelica.SIunits.Density rho_nominal=1000
"Density, used to compute fluid mass";
Buildings.Fluid.FixedResistances.PressureDrop dpIn1(
redeclare package Medium = Medium,
dp_nominal=1000,
m_flow_nominal=0.5*m_flow_nominal) "Pressure drop";
Buildings.Fluid.Movers.SpeedControlled_y floMac1(
redeclare package Medium = Medium,
per(pressure(V_flow={0, m_flow_nominal/rho_nominal}, dp={2*4*1000, 0})),
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial)
"Model of a flow machine";
Buildings.Fluid.FixedResistances.PressureDrop dpOut1(
redeclare package Medium = Medium,
dp_nominal=1000,
m_flow_nominal=0.5*m_flow_nominal) "Pressure drop";
Buildings.Fluid.Sources.Boundary_pT sou(
redeclare package Medium = Medium,
use_p_in=false,
nPorts=2,
T=293.15);
Buildings.Fluid.FixedResistances.PressureDrop dpIn(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=1000) "Pressure drop";
Buildings.Fluid.FixedResistances.PressureDrop dpOut3(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dp_nominal=1000) "Pressure drop";
Buildings.Fluid.FixedResistances.PressureDrop dpIn2(
redeclare package Medium = Medium,
dp_nominal=1000,
m_flow_nominal=0.5*m_flow_nominal) "Pressure drop";
Buildings.Fluid.Movers.SpeedControlled_y floMac2(
redeclare package Medium = Medium,
per(pressure(V_flow={0, m_flow_nominal/rho_nominal}, dp={2*4*1000, 0})),
energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
inputType=Buildings.Fluid.Types.InputType.Constant) "Model of a flow machine";
Buildings.Fluid.FixedResistances.PressureDrop dpOut2(
redeclare package Medium = Medium,
dp_nominal=1000,
m_flow_nominal=0.5*m_flow_nominal) "Pressure drop";
Modelica.Blocks.Sources.Step const1(
height=-1,
offset=1,
startTime=150);
equation
connect(dpIn1.port_b, floMac1.port_a);
connect(floMac1.port_b, dpOut1.port_a);
connect(sou.ports[1], dpIn.port_a);
connect(dpIn.port_b, dpIn1.port_a);
connect(dpOut1.port_b, dpOut3.port_a);
connect(dpOut3.port_b, sou.ports[2]);
connect(dpIn2.port_b,floMac2. port_a);
connect(floMac2.port_b,dpOut2. port_a);
connect(dpIn.port_b, dpIn2.port_a);
connect(dpOut2.port_b, dpOut3.port_a);
connect(const1.y, floMac1.y);
end PumpsParallel;
Buildings.Fluid.Movers.Examples.PumpsSeries
Two flow machines in series
Information
This example tests the configuration of two flow machines that are installed in series. Both flow machines start with full speed. At t=150 seconds, the speed of the flow machine on the left is reduced to zero. As its speed is reduced, the mass flow rate is reduced. Note that even at zero input, the mass flow rate is non-zero, but the pressure drop of the pumpfloMac1.dp is positive, which means that this pump has a flow resistance.
However, flowMac2.dp is always negative, as this pump has a constant control input of 1.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| MassFlowRate | m_flow_nominal | 1 | Nominal mass flow rate [kg/s] |
| ThermodynamicState | state_start | Medium.setState_pTX(T=Medium... | Start state |
| Density | rho_nominal | Medium.density(state_start) | Density, used to compute fluid mass [kg/m3] |
Modelica definition
model PumpsSeries "Two flow machines in series"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water;
parameter Modelica.SIunits.MassFlowRate m_flow_nominal=1
"Nominal mass flow rate";
Buildings.Fluid.Movers.SpeedControlled_y floMac1(
redeclare package Medium = Medium,
per(pressure(V_flow={0, m_flow_nominal/1000}, dp={2*4*1000, 0})),
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Model of a flow machine";
Buildings.Fluid.Sources.Boundary_pT sou(
redeclare package Medium = Medium,
use_p_in=false,
p(displayUnit="Pa") = 300000,
T=293.15,
nPorts=1);
parameter Medium.ThermodynamicState state_start = Medium.setState_pTX(
T=Medium.T_default,
p=Medium.p_default,
X=Medium.X_default) "Start state";
parameter Modelica.SIunits.Density rho_nominal=Medium.density(
state_start) "Density, used to compute fluid mass";
Buildings.Fluid.Movers.SpeedControlled_y floMac2(
redeclare package Medium = Medium,
per(pressure(V_flow={0, m_flow_nominal/1000}, dp={2*4*1000, 0})),
inputType=Buildings.Fluid.Types.InputType.Constant,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState)
"Model of a flow machine";
Modelica.Blocks.Sources.Step const1(
height=-1,
offset=1,
startTime=150);
Buildings.Fluid.Sources.Boundary_pT sou1(
redeclare package Medium = Medium,
use_p_in=false,
p(displayUnit="Pa") = 300000 + 4000,
T=293.15,
nPorts=1);
equation
connect(const1.y, floMac1.y);
connect(floMac1.port_b, floMac2.port_a);
connect(sou.ports[1], floMac1.port_a);
connect(floMac2.port_b, sou1.ports[1]);
end PumpsSeries;
Buildings.Fluid.Movers.Examples.SpeedControlled_y_pumpCurves
Pumps that illustrates the use of the pump curves
Information
This example demonstrates how the pump curves changes for different (constant) input
signal y.
If y ≥ delta = 0.05, the pump curves are polynomials.
For y < delta = 0.05, the pump curves convert to linear functions to
avoid a singularity at the origin.
Extends from Modelica.Icons.Example (Icon for runnable examples).
Modelica definition
model SpeedControlled_y_pumpCurves
"Pumps that illustrates the use of the pump curves"
extends Modelica.Icons.Example;
package Medium = Buildings.Media.Water "Medium model";
// For OpenModelica, changed m_flow_nominal to a constant. Otherwise
// the translation fails with "Error: Cyclically dependent parameters found"
constant Modelica.SIunits.MassFlowRate m_flow_nominal = 0.5
"Nominal mass flow rate";
// For OpenModelica, changed dp_nominal to a constant. Otherwise
// the compilation fails.
constant Modelica.SIunits.PressureDifference dp_nominal = 10000
"Nominal pressure";
model pumpModel = Buildings.Fluid.Movers.SpeedControlled_y (
redeclare package Medium = Medium,
use_inputFilter=
false,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
per(
pressure(V_flow=2/1000*m_flow_nominal*{0.2, 0.4, 0.6, 0.8},
dp=dp_nominal*{0.9, 0.85, 0.6, 0.2})))
"Declaration of pump model";
pumpModel pum(
inputType=Buildings.Fluid.Types.InputType.Constant,
per(constantSpeed=1)) "Pump";
pumpModel pum1(
inputType=Buildings.Fluid.Types.InputType.Constant,
per(constantSpeed=0.5)) "Pump";
pumpModel pum2(
inputType=Buildings.Fluid.Types.InputType.Constant,
per(constantSpeed=0.05)) "Pump";
pumpModel pum3(
inputType=Buildings.Fluid.Types.InputType.Constant,
per(constantSpeed=0.01)) "Pump";
Modelica.Blocks.Sources.Ramp y(
offset=1,
duration=0.5,
startTime=0.25,
height=-0.999)
"Input signal";
Buildings.Fluid.Sources.Boundary_pT sou(
redeclare package Medium = Medium,
use_p_in=false,
p=300000,
T=293.15,
nPorts=4);
Buildings.Fluid.Sources.Boundary_pT sou1(
redeclare package Medium = Medium,
use_p_in=false,
nPorts=4,
p(displayUnit="Pa") = 300000,
T=293.15);
Buildings.Fluid.Actuators.Valves.TwoWayLinear dp1(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dpValve_nominal=0.01*dp_nominal,
use_inputFilter=false) "Pressure drop";
Buildings.Fluid.Actuators.Valves.TwoWayLinear dp2(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dpValve_nominal=0.01*dp_nominal,
use_inputFilter=false) "Pressure drop";
Buildings.Fluid.Actuators.Valves.TwoWayLinear dp3(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dpValve_nominal=0.01*dp_nominal,
use_inputFilter=false) "Pressure drop";
Buildings.Fluid.Actuators.Valves.TwoWayLinear dp4(
redeclare package Medium = Medium,
m_flow_nominal=m_flow_nominal,
dpValve_nominal=0.01*dp_nominal,
use_inputFilter=false) "Pressure drop";
equation
connect(dp1.port_b, pum.port_a);
connect(dp1.port_a, sou.ports[1]);
connect(y.y, dp1.y);
connect(dp2.port_b, pum1.port_a);
connect(y.y,dp2. y);
connect(sou.ports[2], dp2.port_a);
connect(dp3.port_b, pum2.port_a);
connect(y.y,dp3. y);
connect(dp3.port_a, sou.ports[3]);
connect(dp4.port_b, pum3.port_a);
connect(y.y,dp4. y);
connect(dp4.port_a, sou.ports[4]);
connect(pum3.port_b, sou1.ports[1]);
connect(pum2.port_b, sou1.ports[2]);
connect(pum1.port_b, sou1.ports[3]);
connect(pum.port_b, sou1.ports[4]);
end SpeedControlled_y_pumpCurves;
Buildings.Fluid.Movers.Examples.SpeedControlled_y_pumpCurves.pumpModel
Declaration of pump model
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| replaceable package Medium | PartialMedium | Medium in the component | |
| Boolean | addPowerToMedium | true | Set to false to avoid any power (=heat and flow work) being added to medium (may give simpler equations) |
| Control | |||
| InputType | inputType | Buildings.Fluid.Types.InputT... | Control input type |
| Dynamics | |||
| Equations | |||
| Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamic... | Type of energy balance: dynamic (3 initialization options) or steady state |
| Dynamics | massDynamics | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state |
| Nominal condition | |||
| Time | tau | 1 | Time constant of fluid volume for nominal flow, used if energy or mass balance is dynamic [s] |
| Filtered speed | |||
| Boolean | use_inputFilter | false | = true, if speed is filtered with a 2nd order CriticalDamping filter |
| Time | riseTime | 30 | Rise time of the filter (time to reach 99.6 % of the speed) [s] |
| Init | init | Modelica.Blocks.Types.Init.I... | Type of initialization (no init/steady state/initial state/initial output) |
| Real | y_start | 0 | Initial value of speed [1] |
| Initialization | |||
| AbsolutePressure | p_start | Medium.p_default | Start value of pressure [Pa] |
| Temperature | T_start | Medium.T_default | Start value of temperature [K] |
| MassFraction | X_start[Medium.nX] | Medium.X_default | Start value of mass fractions m_i/m [kg/kg] |
| ExtraProperty | C_start[Medium.nC] | fill(0, Medium.nC) | Start value of trace substances |
| ExtraProperty | C_nominal[Medium.nC] | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Assumptions | |||
| Boolean | allowFlowReversal | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Advanced | |||
| MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow [kg/s] |
| Diagnostics | |||
| Boolean | show_T | false | = true, if actual temperature at port is computed |
Connectors
| Type | Name | Description |
|---|---|---|
| replaceable package Medium | Medium in the component | |
| FluidPort_a | port_a | Fluid connector a (positive design flow direction is from port_a to port_b) |
| FluidPort_b | port_b | Fluid connector b (positive design flow direction is from port_a to port_b) |
| input IntegerInput | stage | Stage input signal for the pressure head |
| output RealOutput | y_actual | Actual normalised pump speed that is used for computations [1] |
| output RealOutput | P | Electrical power consumed [W] |
| HeatPort_a | heatPort | Heat dissipation to environment |
| input RealInput | y | Constant normalized rotational speed [1] |
Modelica definition
model pumpModel = Buildings.Fluid.Movers.SpeedControlled_y (
redeclare package Medium = Medium,
use_inputFilter=
false,
energyDynamics=Modelica.Fluid.Types.Dynamics.SteadyState,
per(
pressure(V_flow=2/1000*m_flow_nominal*{0.2, 0.4, 0.6, 0.8},
dp=dp_nominal*{0.9, 0.85, 0.6, 0.2})))
"Declaration of pump model";