JunctionParallelChannels1Phase

This is a volume junction that connects an arbitrary number of parallel channels. If modeling elbows or tees, VolumeJunction1Phase must be used instead.

This component can be used to model an abrupt flow area change, a plenum that is divided into several channels, or a plenum that combines several channels into one. Figure 1 shows the channel configuration appropriate for this junction.

Figure 1: Junction with parallel flow channels.

Usage

The parameter "connections" specifies ends of flow channel components to connect.

The parameter "volume" specifies the volume of the junction, and the parameter "position" specifies the spatial location of the center of the junction, which is used for plotting purposes only.

note:Order-dependent connections

Several quantities in the form loss source terms given by Eq. (3) and Eq. (4) are taken from the first connection in "connections", so using different connections in the first entry gives different results.

The parameter "A_ref" is the reference cross-sectional area $var element = document.getElementById("moose-equation-08336fc9-c142-48cd-9c36-430bc6ace33f");katex.render("A_\\text{ref}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ used in Eq. (3) and Eq. (4). If it is not provided, the cross-sectional area of the first connection in "connections" is used.

A form loss coefficient $var element = document.getElementById("moose-equation-e9ea64a4-5c3a-46dc-b783-75248890b5f1");katex.render("K", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ may be specified using the parameter "K".

Initial conditions are specified with the following parameters:

"initial_T": temperature
"initial_p": pressure
"initial_vel_x": x-velocity
"initial_vel_y": y-velocity
"initial_vel_z": z-velocity

The "apply_velocity_scaling" parameter specifies whether to apply the scaling of Hong and Kim (2011) to the normal component of the velocity of the junction state, as described in Volume Junction.

Input Parameters

connectionsJunction connections
C++ Type:std::vector<BoundaryName>
Unit:(no unit assumed)
Controllable:No
Description:Junction connections
positionSpatial position of the center of the junction [m]
C++ Type:libMesh::Point
Unit:(no unit assumed)
Controllable:No
Description:Spatial position of the center of the junction [m]
volumeVolume of the junction [m^3]
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Volume of the junction [m^3]

Required Parameters

A_refReference area [m^2]
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Reference area [m^2]
K0Form loss factor [-]
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:Yes
Description:Form loss factor [-]
apply_velocity_scalingFalseSet to true to apply the scaling to the normal velocity. See documentation for more information.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Set to true to apply the scaling to the normal velocity. See documentation for more information.
initial_TInitial temperature [K]
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Initial temperature [K]
initial_pInitial pressure [Pa]
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Initial pressure [Pa]
initial_vel_xInitial velocity in x-direction [m/s]
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Initial velocity in x-direction [m/s]
initial_vel_yInitial velocity in y-direction [m/s]
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Initial velocity in y-direction [m/s]
initial_vel_zInitial velocity in z-direction [m/s]
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Initial velocity in z-direction [m/s]
scaling_factor_rhoEV1Scaling factor for rho*E*V [-]
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Scaling factor for rho*E*V [-]
scaling_factor_rhoV1Scaling factor for rho*V [-]
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Scaling factor for rho*V [-]
scaling_factor_rhouV1Scaling factor for rho*u*V [-]
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Scaling factor for rho*u*V [-]
scaling_factor_rhovV1Scaling factor for rho*v*V [-]
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Scaling factor for rho*v*V [-]
scaling_factor_rhowV1Scaling factor for rho*w*V [-]
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Scaling factor for rho*w*V [-]
use_scalar_variablesTrueTrue if the junction variables are scalar variables
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:True if the junction variables are scalar variables

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

Formulation

The junction equations are derived by integrating the conservation equations over the junction volume. This formulation assumes that all connected channels have the same flow direction. For the momentum equation, the term $var element = document.getElementById("moose-equation-6390ae8c-7bf0-4956-9950-869d13710b69");katex.render("\\int_{\\Gamma_{\\text{wall}}}{p\\bf{n}}{d\\Gamma}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ must be evaluated. For this junction, it is assumed that there is an abrupt flow area change within the junction. For the case where the inlet flow area is smaller than the outlet flow area, the geometry of the junction is shown below.

It is assumed that the wall pressure is:

constant and equal to the inlet pressure upstream of the area change.
constant and equal to the outlet pressure downstream the area change.

Then the term $var element = document.getElementById("moose-equation-f52dbd28-f422-46ac-9a6c-a966217cef93");katex.render("\\int_{\\Gamma_{\\text{wall}}}{p\\bf{n}}{d\\Gamma}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is reduced to the surface that is in red in the above diagram.

If the outlet flow area is greater than the inlet flow area, the wall pressure integral projected in the flow direction is:

(1)var element = document.getElementById("moose-equation-59754797-02e3-4217-aba3-b22aeedc3330");katex.render("\\int_{\\Gamma_{\\text{wall}}}{p n_{\\text{flow}}}{d\\Gamma} = - p_{\\text{wall}} A_{\\text{wall}} =-p_{\\text{out}} \\left(A_{\\text{out}}-A_{\\text{in}}\\right)", element, {displayMode:true,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});

If the outlet flow area is smaller than the inlet flow area, the wall pressure integral projected in the flow direction is:

(2)var element = document.getElementById("moose-equation-b61625da-5665-4fb0-8992-2aefa9f3c128");katex.render("\\int_{\\Gamma_{\\text{wall}}}{p n_{\\text{flow}}}{d\\Gamma} = p_{\\text{wall}} A_{\\text{wall}} =p_{\\text{in}} \\left(A_{\\text{in}}-A_{\\text{out}}\\right)", element, {displayMode:true,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});

Form Loss

Complex multidimensional interactions inside the junction cannot be practically modeled mechanistically but are instead approximated using a form loss factor $var element = document.getElementById("moose-equation-287b0085-b893-447a-990d-cddc933f3d61");katex.render("K", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ , which gives rise to source terms on the momentum and energy equations:

(3)var element = document.getElementById("moose-equation-f72132cc-ee3a-4526-bb6e-8d57b71be5f5");katex.render("\\mathbf{S}^{\\text{momentum}} = - K (p_{0,1} - p_1) A_\\text{ref} \\frac{\\mathbf{u}_1}{\\|\\mathbf{u}_1\\|} \\eqc", element, {displayMode:true,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});

(4)var element = document.getElementById("moose-equation-5b6ef6bc-2f25-4624-9fbc-c5c3558fefec");katex.render("S^{\\text{energy}} = - K (p_{0,1} - p_1) A_\\text{ref} \\|\\mathbf{u}_1\\| \\eqc", element, {displayMode:true,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});

where

$var element = document.getElementById("moose-equation-96c34efa-dcb5-493c-854d-9b64ca25eac0");katex.render("p_{0,1}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the stagnation pressure of the first flow channel (see Usage),
$var element = document.getElementById("moose-equation-a0786d40-b7a3-48de-8464-e2b6175c53c9");katex.render("p_1", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the static pressure of the first flow channel,
$var element = document.getElementById("moose-equation-34a50e98-b5f9-40f5-a52a-4d8ce7b8d7f3");katex.render("A_\\text{ref}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the reference cross-sectional area, and
$var element = document.getElementById("moose-equation-473850b2-10e6-4879-a3a5-9b746dd72792");katex.render("\\mathbf{u}_1", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ is the velocity in the first connected flow channel.

Input Files

(modules/thermal_hydraulics/tutorials/single_phase_flow/04_loop.i)
(modules/thermal_hydraulics/tutorials/single_phase_flow/06_custom_closures.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/phy.shower.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/jac.test.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/phy.unequal_area.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/junction_with_calorifically_imperfect_gas.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/err.missing_ics.i)
(modules/thermal_hydraulics/tutorials/single_phase_flow/05_secondary_side.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/conservation.i)
(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/equal_area_with_junction.i)
(modules/thermal_hydraulics/tutorials/single_phase_flow/03_upper_loop.i)

Child Objects

(modules/thermal_hydraulics/include/components/SimpleTurbine1Phase.h)

References

Seok Hong and Chongam Kim. A new finite volume method on junction coupling and boundary treatment for flow network system analyses. International Journal for Numerical Methods in Fluids, 65:707 – 742, 02 2011. doi:10.1002/fld.2212.

@article{hong2011,
    author = "Hong, Seok and Kim, Chongam",
    year = "2011",
    month = "02",
    pages = "707 - 742",
    title = "A new finite volume method on junction coupling and boundary treatment for flow network system analyses",
    volume = "65",
    journal = "International Journal for Numerical Methods in Fluids",
    doi = "10.1002/fld.2212"
}

(modules/thermal_hydraulics/tutorials/single_phase_flow/04_loop.i)

T_in = 300. # K
m_dot_in = 1e-2 # kg/s
press = 10e5 # Pa

# core parameters
core_length = 1. # m
core_n_elems = 25
core_dia = '${units 2. cm -> m}'
core_pitch = '${units 8.7 cm -> m}'

# pipe parameters
pipe_dia = '${units 10. cm -> m}'
A_pipe = '${fparse 0.25 * pi * pipe_dia^2}'
A_core = '${fparse core_pitch^2 - 0.25 *pi * core_dia^2}'
P_wet_core = '${fparse 4*core_pitch + pi * core_dia}'
Dh_core = '${fparse 4 * A_core / P_wet_core}'

tot_power = 2000 # W

[GlobalParams]
  initial_p = ${press}
  initial_vel = 0.0001
  initial_T = ${T_in}
  initial_vel_x = 0
  initial_vel_y = 0
  initial_vel_z = 0
  gravity_vector = '0 0 0'

  rdg_slope_reconstruction = minmod
  scaling_factor_1phase = '1 1e-2 1e-4'
  scaling_factor_rhoV = 1
  scaling_factor_rhouV = 1e-2
  scaling_factor_rhovV = 1e-2
  scaling_factor_rhowV = 1e-2
  scaling_factor_rhoEV = 1e-4
  closures = simple_closures
  fp = he
[]

[FluidProperties]
  [he]
    type = IdealGasFluidProperties
    molar_mass = 4e-3
    gamma = 1.67
    k = 0.2556
    mu = 3.22639e-5
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseTHM
  []
[]

[SolidProperties]
  [steel]
    type = ThermalFunctionSolidProperties
    rho = 8050
    k = 45
    cp = 466
  []
[]

[Components]
  [total_power]
    type = TotalPower
    power = ${tot_power}
  []
  [up_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 15
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct1]
    type = JunctionParallelChannels1Phase
    position = '0 0 0.5'
    connections = 'up_pipe_1:out core_chan:in'
    volume = 1e-5
    use_scalar_variables = false
  []
  [core_chan]
    type = FlowChannel1Phase
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    roughness = .0001
    A = '${A_core}'
    D_h = ${Dh_core}
  []

  [core_hs]
    type = HeatStructureCylindrical
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    names = 'block'
    widths = '${fparse core_dia / 2.}'
    solid_properties = 'steel'
    solid_properties_T_ref = '300'
    n_part_elems = 3
  []

  [core_heating]
    type = HeatSourceFromTotalPower
    hs = core_hs
    regions = block
    power = total_power
  []

  [core_ht]
    type = HeatTransferFromHeatStructure1Phase
    flow_channel = core_chan
    hs = core_hs
    hs_side = outer
    P_hf = '${fparse pi * core_dia}'
  []

  [jct2]
    type = JunctionParallelChannels1Phase
    position = '0 0 1.5'
    connections = 'core_chan:out up_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [up_pipe_2]
    type = FlowChannel1Phase
    position = '0 0 1.5'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct3]
    type = JunctionOneToOne1Phase
    connections = 'up_pipe_2:out top_pipe_1:in'
  []

  [top_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [top_pipe_2]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct4]
    type = VolumeJunction1Phase
    position = '0.5 0 2'
    volume = 1e-5
    connections = 'top_pipe_1:out top_pipe_2:in press_pipe:in'
    use_scalar_variables = false
  []

  [press_pipe]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '0 0 1'
    length = 0.2
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pressurizer]
    type = InletStagnationPressureTemperature1Phase
    p0 = ${press}
    T0 = ${T_in}
    input = press_pipe:out
  []

  [jct5]
    type = JunctionOneToOne1Phase
    connections = 'top_pipe_2:out down_pipe_1:in'
  []

  [down_pipe_1]
    type = FlowChannel1Phase
    position = '1 0 2'
    orientation = '0 0 -1'
    length = 0.25
    A = ${A_pipe}
    n_elems = 5
  []

  [jct6]
    type = JunctionOneToOne1Phase
    connections = 'down_pipe_1:out cooling_pipe:in'
  []

  [cooling_pipe]
    type = FlowChannel1Phase
    position = '1 0 1.75'
    orientation = '0 0 -1'
    length = 1.5
    n_elems = 25
    A = ${A_pipe}
  []

  [cold_wall]
    type = HeatTransferFromSpecifiedTemperature1Phase
    flow_channel = cooling_pipe
    T_wall = 300
    P_hf = '${fparse pi * pipe_dia}'
  []

  [jct7]
    type = JunctionOneToOne1Phase
    connections = 'cooling_pipe:out down_pipe_2:in'
  []

  [down_pipe_2]
    type = FlowChannel1Phase
    position = '1 0 0.25'
    orientation = '0 0 -1'
    length = 0.25
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct8]
    type = JunctionOneToOne1Phase
    connections = 'down_pipe_2:out bottom_1:in'
  []

  [bottom_1]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pump]
    type = Pump1Phase
    position = '0.5 0 0'
    connections = 'bottom_1:out bottom_2:in'
    volume = 1e-4
    A_ref = ${A_pipe}
    head = 0
    use_scalar_variables = false
  []

  [bottom_2]
    type = FlowChannel1Phase
    position = '0.5 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct10]
    type = JunctionOneToOne1Phase
    connections = 'bottom_2:out up_pipe_1:in'
  []
[]

[ControlLogic]
  [set_point]
    type = GetFunctionValueControl
    function = ${m_dot_in}
  []

  [pid]
    type = PIDControl
    initial_value = 0
    set_point = set_point:value
    input = m_dot_pump
    K_p = 1.
    K_i = 4.
    K_d = 0
  []

  [set_pump_head]
    type = SetComponentRealValueControl
    component = pump
    parameter = head
    value = pid:output
  []
[]

[Postprocessors]
  [power_to_coolant]
    type = ADHeatRateConvection1Phase
    block = core_chan
    P_hf = '${fparse pi *core_dia}'
  []

  [m_dot_pump]
    type = ADFlowJunctionFlux1Phase
    boundary = core_chan:in
    connection_index = 1
    equation = mass
    junction = jct7
  []

  [core_T_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = T
  []

  [core_p_in]
    type = SideAverageValue
    boundary = core_chan:in
    variable = p
  []

  [core_p_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = p
  []

  [core_delta_p]
    type = ParsedPostprocessor
    pp_names = 'core_p_in core_p_out'
    expression = 'core_p_in - core_p_out'
  []

  [hx_pri_T_out]
    type = SideAverageValue
    boundary = cooling_pipe:out
    variable = T
  []
  [pump_head]
    type = RealComponentParameterValuePostprocessor
    component = pump
    parameter = head
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  start_time = 0

  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1
  []
  dtmax = 5
  end_time = 500

  line_search = basic
  solve_type = NEWTON

  petsc_options_iname = '-pc_type'
  petsc_options_value = 'lu'

  nl_rel_tol = 0
  nl_abs_tol = 1e-8
  nl_max_its = 25

[]

[Outputs]
  exodus = true

  [console]
    type = Console
    max_rows = 1
    outlier_variable_norms = false
  []
  print_linear_residuals = false
[]

(modules/thermal_hydraulics/tutorials/single_phase_flow/06_custom_closures.i)

T_in = 300. # K
m_dot_in = 1e-2 # kg/s
press = 10e5 # Pa

# core parameters
core_length = 1. # m
core_n_elems = 25
core_dia = '${units 2. cm -> m}'
core_pitch = '${units 8.7 cm -> m}'
A_core = '${fparse core_pitch^2 - 0.25 *pi * core_dia^2}'
P_wet_core = '${fparse 4*core_pitch + pi * core_dia}'
Dh_core = '${fparse 4 * A_core / P_wet_core}'

# pipe parameters
pipe_dia = '${units 10. cm -> m}'
A_pipe = '${fparse 0.25 * pi * pipe_dia^2}'

tot_power = 2000 # W

# heat exchanger parameters
hx_dia_inner = '${units 12. cm -> m}'
hx_wall_thickness = '${units 5. mm -> m}'
hx_dia_outer = '${units 50. cm -> m}'
hx_radius_wall = '${fparse hx_dia_inner / 2. + hx_wall_thickness}'
hx_length = 1.5 # m
hx_n_elems = 25

m_dot_sec_in = 1. # kg/s

[GlobalParams]
  initial_p = ${press}
  initial_vel = 0.0001
  initial_T = ${T_in}
  initial_vel_x = 0
  initial_vel_y = 0
  initial_vel_z = 0
  gravity_vector = '0 0 0'

  rdg_slope_reconstruction = minmod
  scaling_factor_1phase = '1 1e-2 1e-4'
  scaling_factor_rhoV = 1
  scaling_factor_rhouV = 1e-2
  scaling_factor_rhovV = 1e-2
  scaling_factor_rhowV = 1e-2
  scaling_factor_rhoEV = 1e-4
  closures = thm_closures
  fp = he
[]

[Functions]
  [m_dot_sec_fn]
    type = PiecewiseLinear
    xy_data = '
      0    0
      10 ${m_dot_sec_in}'
  []
[]

[FluidProperties]
  [he]
    type = IdealGasFluidProperties
    molar_mass = 4e-3
    gamma = 1.67
    k = 0.2556
    mu = 3.22639e-5
  []

  [water]
    type = StiffenedGasFluidProperties
    gamma = 2.35
    cv = 1816.0
    q = -1.167e6
    p_inf = 1.0e9
    q_prime = 0
  []
[]

[Closures]
  [thm_closures]
    type = Closures1PhaseTHM
  []
  [none_closures]
    type = Closures1PhaseNone
  []
[]

[Materials]
  [Re_mat]
    type = ADReynoldsNumberMaterial
    Re = Re
    rho = rho
    vel = vel
    D_h = D_h
    mu = mu
    block = hx/pri
  []
  [f_mat]
    type = ADParsedMaterial
    property_name = f_D
    constant_names = 'a b c'
    constant_expressions = '1 0.1 -0.5'
    material_property_names = 'Re'
    expression = 'a + b * Re^c'
    block = hx/pri
  []
  [Pr_mat]
    type = ADPrandtlNumberMaterial
    Pr = Pr
    cp = cp
    mu = mu
    k = k
    block = hx/pri
  []
  [Nu_mat]
    type = ADParsedMaterial
    property_name = 'Nu'
    constant_names = 'a b c'
    constant_expressions = '0.03 0.9 0.5'
    material_property_names = 'Re Pr'
    expression = 'a * Re ^b * Pr^c'
    block = hx/pri
  []
  [Hw_mat]
    type = ADConvectiveHeatTransferCoefficientMaterial
    D_h = D_h
    k = k
    Nu = Nu
    Hw = Hw
    block = hx/pri
  []
[]
[SolidProperties]
  [steel]
    type = ThermalFunctionSolidProperties
    rho = 8050
    k = 45
    cp = 466
  []
[]

[Components]
  [total_power]
    type = TotalPower
    power = ${tot_power}
  []
  [up_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 15
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct1]
    type = JunctionParallelChannels1Phase
    position = '0 0 0.5'
    connections = 'up_pipe_1:out core_chan:in'
    volume = 1e-5
    use_scalar_variables = false
  []
  [core_chan]
    type = FlowChannel1Phase
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    roughness = .0001
    A = ${A_core}
    D_h = ${Dh_core}
  []

  [core_hs]
    type = HeatStructureCylindrical
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    names = 'block'
    widths = '${fparse core_dia / 2.}'
    solid_properties = 'steel'
    solid_properties_T_ref = '300'
    n_part_elems = 3
  []

  [core_heating]
    type = HeatSourceFromTotalPower
    hs = core_hs
    regions = block
    power = total_power
  []

  [core_ht]
    type = HeatTransferFromHeatStructure1Phase
    flow_channel = core_chan
    hs = core_hs
    hs_side = outer
    P_hf = '${fparse pi * core_dia}'
  []

  [jct2]
    type = JunctionParallelChannels1Phase
    position = '0 0 1.5'
    connections = 'core_chan:out up_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [up_pipe_2]
    type = FlowChannel1Phase
    position = '0 0 1.5'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct3]
    type = JunctionOneToOne1Phase
    connections = 'up_pipe_2:out top_pipe_1:in'
  []

  [top_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [top_pipe_2]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct4]
    type = VolumeJunction1Phase
    position = '0.5 0 2'
    volume = 1e-5
    connections = 'top_pipe_1:out top_pipe_2:in press_pipe:in'
    use_scalar_variables = false
  []

  [press_pipe]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '0 1 0'
    length = 0.2
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pressurizer]
    type = InletStagnationPressureTemperature1Phase
    p0 = ${press}
    T0 = ${T_in}
    input = press_pipe:out
  []

  [jct5]
    type = JunctionOneToOne1Phase
    connections = 'top_pipe_2:out down_pipe_1:in'
  []

  [down_pipe_1]
    type = FlowChannel1Phase
    position = '1 0 2'
    orientation = '0 0 -1'
    length = 0.25
    A = ${A_pipe}
    n_elems = 5
  []

  [jct6]
    type = JunctionParallelChannels1Phase
    position = '1 0 1.75'
    connections = 'down_pipe_1:out hx/pri:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [hx]
    [pri]
      type = FlowChannel1Phase
      position = '1 0 1.75'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      roughness = 1e-5
      A = '${fparse pi * hx_dia_inner * hx_dia_inner / 4.}'
      D_h = ${hx_dia_inner}
      closures = none_closures
    []

    [ht_pri]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = inner
      flow_channel = hx/pri
      P_hf = '${fparse pi * hx_dia_inner}'
    []

    [wall]
      type = HeatStructureCylindrical
      position = '1 0 1.75'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      widths = '${hx_wall_thickness}'
      n_part_elems = '3'
      solid_properties = 'steel'
      solid_properties_T_ref = '300'
      names = '0'
      inner_radius = '${fparse hx_dia_inner / 2.}'
    []

    [ht_sec]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = outer
      flow_channel = hx/sec
      P_hf = '${fparse 2 * pi * hx_radius_wall}'
    []

    [sec]
      type = FlowChannel1Phase
      position = '${fparse 1 + hx_wall_thickness} 0 0.25'
      orientation = '0 0 1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      A = '${fparse pi * (hx_dia_outer * hx_dia_outer / 4. - hx_radius_wall * hx_radius_wall)}'
      D_h = '${fparse hx_dia_outer - (2 * hx_radius_wall)}'
      fp = water
      initial_T = 300
    []
  []

  [jct7]
    type = JunctionParallelChannels1Phase
    position = '1 0 0.5'
    connections = 'hx/pri:out down_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [down_pipe_2]
    type = FlowChannel1Phase
    position = '1 0 0.25'
    orientation = '0 0 -1'
    length = 0.25
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct8]
    type = JunctionOneToOne1Phase
    connections = 'down_pipe_2:out bottom_1:in'
  []

  [bottom_1]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pump]
    type = Pump1Phase
    position = '0.5 0 0'
    connections = 'bottom_1:out bottom_2:in'
    volume = 1e-4
    A_ref = ${A_pipe}
    head = 0
    use_scalar_variables = false
  []

  [bottom_2]
    type = FlowChannel1Phase
    position = '0.5 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct9]
    type = JunctionOneToOne1Phase
    connections = 'bottom_2:out up_pipe_1:in'
  []

  [inlet_sec]
    type = InletMassFlowRateTemperature1Phase
    input = 'hx/sec:in'
    m_dot = 0
    T = 300
  []

  [outlet_sec]
    type = Outlet1Phase
    input = 'hx/sec:out'
    p = 1e5
  []
[]

[ControlLogic]
  [set_point]
    type = GetFunctionValueControl
    function = ${m_dot_in}
  []

  [pid]
    type = PIDControl
    initial_value = 0.0
    set_point = set_point:value
    input = m_dot_pump
    K_p = 1.
    K_i = 4.
    K_d = 0
  []

  [set_pump_head]
    type = SetComponentRealValueControl
    component = pump
    parameter = head
    value = pid:output
  []

  [m_dot_sec_inlet_ctrl]
    type = GetFunctionValueControl
    function = m_dot_sec_fn
  []

  [set_m_dot_sec_ctrl]
    type = SetComponentRealValueControl
    component = inlet_sec
    parameter = m_dot
    value = m_dot_sec_inlet_ctrl:value
  []
[]

[Postprocessors]
  [power_to_coolant]
    type = ADHeatRateConvection1Phase
    block = core_chan
    P_hf = '${fparse pi *core_dia}'
  []

  [m_dot_pump]
    type = ADFlowJunctionFlux1Phase
    boundary = core_chan:in
    connection_index = 1
    equation = mass
    junction = jct7
  []

  [core_T_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = T
  []

  [core_p_in]
    type = SideAverageValue
    boundary = core_chan:in
    variable = p
  []

  [core_p_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = p
  []

  [core_delta_p]
    type = ParsedPostprocessor
    pp_names = 'core_p_in core_p_out'
    expression = 'core_p_in - core_p_out'
  []

  [hx_pri_T_out]
    type = SideAverageValue
    boundary = hx/pri:out
    variable = T
  []

  [hx_sec_T_in]
    type = SideAverageValue
    boundary = inlet_sec
    variable = T
  []

  [hx_sec_T_out]
    type = SideAverageValue
    boundary = outlet_sec
    variable = T
  []
  [m_dot_sec]
    type = ADFlowBoundaryFlux1Phase
    boundary = inlet_sec
    equation = mass
  []

  [Hw_hx_pri]
    type = ADElementAverageMaterialProperty
    mat_prop = Hw
    block = hx/pri
  []
  [fD_hx_pri]
    type = ADElementAverageMaterialProperty
    mat_prop = f_D
    block = hx/pri
  []

[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  start_time = 0

  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1
  []
  dtmax = 5
  end_time = 500

  line_search = basic
  solve_type = NEWTON

  petsc_options_iname = '-pc_type'
  petsc_options_value = 'lu'

  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-8
  nl_max_its = 25

[]

[Outputs]
  exodus = true

  [console]
    type = Console
    max_rows = 1
    outlier_variable_norms = false
  []
  print_linear_residuals = false
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/phy.shower.i)

# This problem models a "shower": water from two pipes, one hot and one cold,
# mixes together to produce a temperature between the two.

[GlobalParams]
  gravity_vector = '0 0 0'

  initial_T = 300
  initial_p = 1e5
  initial_vel = 1
  initial_vel_x = 1
  initial_vel_y = 0
  initial_vel_z = 0

  # global parameters for pipes
  fp = eos
  orientation = '1 0 0'
  length = 1
  n_elems = 20
  f = 0

  scaling_factor_1phase = '1 1 1e-6'

  closures = simple_closures
[]

[FluidProperties]
  [eos]
    type = IdealGasFluidProperties
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Components]
  [inlet_hot]
    type = InletDensityVelocity1Phase
    input = 'pipe_hot:in'
    # rho @ (p = 1e5, T = 310 K)
    rho = 1315.9279785683
    vel = 1
  []
  [inlet_cold]
    type = InletDensityVelocity1Phase
    input = 'pipe_cold:in'
    # rho @ (p = 1e5, T = 280 K)
    rho = 1456.9202619863
    vel = 1
  []
  [outlet]
    type = Outlet1Phase
    input = 'pipe_warm:out'
    p = 1e5
  []

  [pipe_hot]
    type = FlowChannel1Phase
    position = '0 1 0'
    A = 1
  []
  [pipe_cold]
    type = FlowChannel1Phase
    position = '0 0 0'
    A = 1
  []
  [pipe_warm]
    type = FlowChannel1Phase
    position = '1 0.5 0'
    A = 2
    initial_vel = 0.5
  []

  [junction]
    type = JunctionParallelChannels1Phase
    connections = 'pipe_cold:out pipe_hot:out pipe_warm:in'
    position = '1 0.5 0'
    volume = 1e-8
    use_scalar_variables = false
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  scheme = 'bdf2'

  solve_type = 'NEWTON'
  line_search = 'basic'
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-5
  nl_max_its = 10

  l_tol = 1e-2
  l_max_its = 10

  start_time = 0
  end_time = 5
  dt = 0.05

  abort_on_solve_fail = true
[]

[Postprocessors]
  # These post-processors are used to test that the energy flux on
  # the warm side of the junction is equal to the sum of the energy
  # fluxes of the hot and cold inlets to the junction.
  [energy_flux_hot]
    type = EnergyFluxIntegral
    boundary = pipe_hot:out
    arhouA = rhouA
    H = H
  []
  [energy_flux_cold]
    type = EnergyFluxIntegral
    boundary = pipe_cold:out
    arhouA = rhouA
    H = H
  []
  [energy_flux_warm]
    type = EnergyFluxIntegral
    boundary = pipe_warm:in
    arhouA = rhouA
    H = H
  []
  [energy_flux_inlet_sum]
    type = SumPostprocessor
    values = 'energy_flux_hot energy_flux_cold'
  []
  [test_rel_err]
    type = RelativeDifferencePostprocessor
    value1 = energy_flux_warm
    value2 = energy_flux_inlet_sum
  []
[]

[Outputs]
  [out]
    type = CSV
    show = test_rel_err
    sync_only = true
    sync_times = '3 4 5'
  []
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/jac.test.i)

# Pump data used in this test comes from the LOFT Systems Tests, described in NUREG/CR-0247

[GlobalParams]
  initial_p = 1e5
  initial_T = 300
  initial_vel = 1

  closures = simple_closures
  fp = fp
  f = 0

  scaling_factor_1phase = '1e-2 1e-2 1e-5'
  scaling_factor_rhoEV = 1e-5
[]

[FluidProperties]
  [fp]
    type = StiffenedGasFluidProperties
    gamma = 2.35
    q = -1167e3
    q_prime = 0
    p_inf = 1.e9
    cv = 1816
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Components]
  [in]
    type = InletStagnationPressureTemperature1Phase
    input = fch1:in
    p0 = 1.1e5
    T0 = 300
  []

  [fch1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '1 0 0'
    length = 1
    n_elems = 1
    A = 1
  []

  [junction]
    type = JunctionParallelChannels1Phase
    connections = 'fch1:out fch2:in'
    position = '1 0 0'
    volume = 0.3
    initial_vel_x = 1
    initial_vel_y = 0
    initial_vel_z = 0
    use_scalar_variables = false
  []

  [fch2]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '1 0 0'
    length = 1
    n_elems = 1
    A = 1.5
  []

  [out]
    type = Outlet1Phase
    input = fch2:out
    p = 1e5
  []
[]


[Preconditioning]
  [SMP_PJFNK]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  scheme = 'bdf2'

  start_time = 0
  num_steps = 1
  abort_on_solve_fail = true
  dt = 0.1

  solve_type = 'newton'
  line_search = 'basic'
  petsc_options_iname = '-snes_test_err'
  petsc_options_value = '1e-9'

  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-6
  nl_max_its = 15

  l_tol = 1e-4
  l_max_its = 10
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/phy.unequal_area.i)

# Junction between 2 pipes where the second has half the area of the first.
# The momentum density of the second should be twice that of the first.

[GlobalParams]
  gravity_vector = '0 0 0'

  initial_T = 300
  initial_p = 1e5
  initial_vel_x = 50
  initial_vel_y = 0
  initial_vel_z = 0

  f = 0

  fp = eos

  scaling_factor_1phase = '1 1e-2 1e-5'

  closures = simple_closures
[]

[FluidProperties]
  [eos]
    type = StiffenedGasFluidProperties
    gamma = 1.4
    cv = 725
    p_inf = 0
    q = 0
    q_prime = 0
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Components]
  [inlet]
    type = InletMassFlowRateTemperature1Phase
    input = 'pipe1:in'
    m_dot = 10
    T = 250
  []

  [pipe1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '1 0 0'
    length = 1
    A = 1
    n_elems = 20
    initial_vel = 20
  []

  [junction]
    type = JunctionParallelChannels1Phase
    connections = 'pipe1:out pipe2:in'
    scaling_factor_rhouV = 1e-4
    scaling_factor_rhoEV = 1e-5
    position = '1 0 0'
    volume = 1e-8
    use_scalar_variables = false
  []

  [pipe2]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '1 0 0'
    length = 1
    A = 0.5
    n_elems = 20
    initial_vel = 15
  []

  [outlet]
    type = Outlet1Phase
    input = 'pipe2:out'
    p = 1e5
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  scheme = 'bdf2'

  solve_type = 'NEWTON'
  line_search = 'basic'
  nl_rel_tol = 0
  nl_abs_tol = 1e-6
  nl_max_its = 15

  l_tol = 1e-10
  l_max_its = 10

  petsc_options_iname = '-pc_type'
  petsc_options_value = 'lu'

  start_time = 0
  end_time = 3
  dt = 0.1

  abort_on_solve_fail = true
[]

[Postprocessors]
  # These post-processors are used to test that the outlet side of the junction,
  # which has half the area of the inlet side, has twice the momentum density
  # that the inlet side does.
  [rhouA_pipe1]
    type = SideAverageValue
    variable = rhouA
    boundary = pipe1:out
  []
  [rhouA_pipe2]
    type = SideAverageValue
    variable = rhouA
    boundary = pipe2:out
  []
  [test_rel_err]
    type = RelativeDifferencePostprocessor
    value1 = rhouA_pipe1
    value2 = rhouA_pipe2
  []
[]

[Outputs]
  [out]
    type = CSV
    show = test_rel_err
    execute_on = 'final'
  []
[]
[Debug]
  show_var_residual_norms = true
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/junction_with_calorifically_imperfect_gas.i)

# This input file tests compatibility of JunctionParallelChannels1Phase and CaloricallyImperfectGas.
# Loss coefficient is applied in first junction.
# Expected pressure drop from form loss ~0.5*K*rho_in*vel_in^2=0.5*100*3.219603*1 = 160.9 Pa
# Pressure drop from averall flow area change ~ 21.9 Pa
# Expected pressure drop ~ 182.8 Pa

T_in = 523.0
vel = 1
p_out = 7e6

[GlobalParams]
  initial_p = ${p_out}
  initial_vel = ${vel}
  initial_T = ${T_in}
  gravity_vector = '0 0 0'
  closures = simple_closures
  n_elems = 3
  f = 0

  scaling_factor_1phase = '1 1 1e-5'
  scaling_factor_rhoV = '1e2'
  scaling_factor_rhowV = '1e-2'
  scaling_factor_rhoEV = '1e-5'
[]

[Functions]
  [e_fn]
    type = PiecewiseLinear
    x = '100   280 300 350 400 450 500 550 600 700 800 900 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 5000'
    y = '783.9 2742.3 2958.6 3489.2 4012.7 4533.3 5053.8 5574 6095.1 7140.2 8192.9 9256.3 10333.6 12543.9 14836.6 17216.3 19688.4 22273.7 25018.3 28042.3 31544.2 35818.1 41256.5 100756.5'
    scale_factor = 1e3
  []

  [mu_fn]
    type = PiecewiseLinear
    x = '100   280 300 350 400 450 500 550 600 700 800 900 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 5000'
    y = '85.42 85.42 89.53 99.44 108.9 117.98 126.73 135.2 143.43 159.25 174.36 188.9 202.96 229.88 255.5 280.05 303.67 326.45 344.97 366.49 387.87 409.48 431.86 431.86'
    scale_factor = 1e-7
  []

  [k_fn]
    type = PiecewiseLinear
    x = '100 280 300 350 400 450 500 550 600 700 800 900 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 5000'
    y = '186.82 186.82 194.11 212.69 231.55 250.38 268.95 287.19 305.11 340.24 374.92 409.66 444.75 511.13 583.42 656.44 733.32 826.53 961.15 1180.38 1546.31 2135.49 3028.08 3028.08'
    scale_factor = 1e-3
  []
[]

[FluidProperties]
  [fp]
    type = CaloricallyImperfectGas
    molar_mass = 0.002
    e = e_fn
    k = k_fn
    mu = mu_fn
    min_temperature = 100
    max_temperature = 5000
    out_of_bound_error = false
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Components]
  [inlet_bc]
    type = InletVelocityTemperature1Phase
    input = 'inlet:in'
    vel = ${vel}
    T = ${T_in}
  []
  [inlet]
    type = FlowChannel1Phase
    fp = fp
    position = '0 0 11'
    orientation = '0 0 -1'
    length = 1
    A = 3
  []
  [inlet_plenum]
    type = JunctionParallelChannels1Phase
    position = '0 0 10'
    initial_vel_x = 0
    initial_vel_y = 0
    initial_vel_z = ${vel}
    K = 100
    connections = 'inlet:out channel1:in channel2:in'
    volume = 1
    use_scalar_variables = false
  []
  [channel1]
    type = FlowChannel1Phase
    fp = fp
    position = '0 0 10'
    orientation = '0 0 -1'
    length = 10
    A = 4
    D_h = 1
  []
  [channel2]
    type = FlowChannel1Phase
    fp = fp
    position = '0 0 10'
    orientation = '0 0 -1'
    length = 10
    A = 1
    D_h = 1
  []
  [outlet_plenum]
    type = JunctionParallelChannels1Phase
    position = '0 0 0'
    initial_vel_x = 1
    initial_vel_y = 0
    initial_vel_z = ${vel}
    connections = 'channel1:out channel2:out outlet:in'
    volume = 1
    use_scalar_variables = false
  []
  [outlet]
    type = FlowChannel1Phase
    fp = fp
    position = '0 0 0'
    orientation = '0 0 -1'
    length = 1
    A = 1
  []
  [outlet_bc]
    type = Outlet1Phase
    p = ${p_out}
    input = 'outlet:out'
  []
[]

[Postprocessors]
  [p_in]
    type = SideAverageValue
    variable = p
    boundary = inlet:in
  []
  [p_out]
    type = SideAverageValue
    variable = p
    boundary = outlet:out
  []
  [Delta_p]
    type = DifferencePostprocessor
    value1 = p_out
    value2 = p_in
  []
  [inlet_in_m_dot]
    type = ADFlowBoundaryFlux1Phase
    boundary = 'inlet_bc'
    equation = mass
  []
  [inlet_out_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'inlet:out'
    connection_index = 0
    junction = inlet_plenum
    equation = mass
  []

  [channel1_in_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'channel1:in'
    connection_index = 1
    junction = inlet_plenum
    equation = mass
  []
  [channel1_out_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'channel1:out'
    connection_index = 0
    junction = outlet_plenum
    equation = mass
  []

  [channel2_in_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'channel2:in'
    connection_index = 2
    junction = inlet_plenum
    equation = mass
  []
  [channel2_out_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'channel2:out'
    connection_index = 1
    junction = outlet_plenum
    equation = mass
  []

  [outlet_in_m_dot]
    type = ADFlowJunctionFlux1Phase
    boundary = 'outlet:in'
    connection_index = 2
    junction = outlet_plenum
    equation = mass
  []
  [outlet_out_m_dot]
    type = ADFlowBoundaryFlux1Phase
    boundary = 'outlet_bc'
    equation = mass
  []

  [net_mass_flow_rate_domain]
    type = LinearCombinationPostprocessor
    pp_names = 'inlet_in_m_dot outlet_out_m_dot'
    pp_coefs = '1 -1'
  []
  [net_mass_flow_rate_volume_junction]
    type = LinearCombinationPostprocessor
    pp_names = 'inlet_out_m_dot channel1_in_m_dot channel2_in_m_dot'
    pp_coefs = '1 -1 -1'
  []
[]

[Preconditioning]
  [smp]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  scheme = bdf2
  start_time = 0
  end_time = 20
  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1
    optimal_iterations = 8
    iteration_window = 2
  []
  timestep_tolerance = 1e-6
  abort_on_solve_fail = true

  line_search = basic
  nl_rel_tol = 1e-8
  nl_abs_tol = 2e-8
  nl_max_its = 25
  l_tol = 1e-3
  l_max_its = 5
  petsc_options = '-snes_converged_reason'
  petsc_options_iname = '-pc_type'
  petsc_options_value = ' lu     '
[]

[Outputs]
  [out]
    type = CSV
    execute_on = 'FINAL'
    show = 'net_mass_flow_rate_domain net_mass_flow_rate_volume_junction Delta_p'
  []
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/err.missing_ics.i)

[GlobalParams]
  gravity_vector = '0 0 0'

  A = 1e-4
  f = 0
  fp = fp

  closures = simple_closures
[]

[FluidProperties]
  [fp]
    type = StiffenedGasFluidProperties
    gamma = 1.4
    cv = 725
    p_inf = 0
    q = 0
    q_prime = 0
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Components]
  [inlet]
    type = InletStagnationPressureTemperature1Phase
    input = 'pipe1:in'
    # Stagnation property with p = 1e5 Pa, T = 250 K, vel = 1 m/s
    p0 = 100000.68965687
    T0 = 250.00049261084
  []

  [pipe1]
    type = FlowChannel1Phase

    position = '0 0 0'
    orientation = '1 0 0'
    length = 1
    n_elems = 2

    initial_p = 1e5
    initial_T = 250
    initial_vel = 0
  []

  [junction]
    type = JunctionParallelChannels1Phase
    connections = 'pipe1:out pipe2:in'
    position = '1.02 0 0'
    volume = 0.1
    use_scalar_variables = false
  []

  [pipe2]
    type = FlowChannel1Phase

    position = '1.04 0 0'
    orientation = '1 0 0'
    length = 0.96
    n_elems = 2

    initial_p = 1e5
    initial_T = 250
    initial_vel = 0
  []

  [outlet]
    type = Outlet1Phase
    input = 'pipe2:out'
    p = 1e5
  []
[]

[Executioner]
  type = Transient
  abort_on_solve_fail = true
[]

(modules/thermal_hydraulics/tutorials/single_phase_flow/05_secondary_side.i)

T_in = 300. # K
m_dot_in = 1e-2 # kg/s
press = 10e5 # Pa

# core parameters
core_length = 1. # m
core_n_elems = 25
core_dia = '${units 2. cm -> m}'
core_pitch = '${units 8.7 cm -> m}'
A_core = '${fparse core_pitch^2 - 0.25 *pi * core_dia^2}'
P_wet_core = '${fparse 4*core_pitch + pi * core_dia}'
Dh_core = '${fparse 4 * A_core / P_wet_core}'

# pipe parameters
pipe_dia = '${units 10. cm -> m}'
A_pipe = '${fparse 0.25 * pi * pipe_dia^2}'

tot_power = 2000 # W

# heat exchanger parameters
hx_dia_inner = '${units 12. cm -> m}'
hx_wall_thickness = '${units 5. mm -> m}'
hx_dia_outer = '${units 50. cm -> m}'
hx_radius_wall = '${fparse hx_dia_inner / 2. + hx_wall_thickness}'
hx_length = 1.5 # m
hx_n_elems = 25

m_dot_sec_in = 1. # kg/s

[GlobalParams]
  initial_p = ${press}
  initial_vel = 0.0001
  initial_T = ${T_in}
  initial_vel_x = 0
  initial_vel_y = 0
  initial_vel_z = 0
  gravity_vector = '0 0 0'

  rdg_slope_reconstruction = minmod
  scaling_factor_1phase = '1 1e-2 1e-4'
  scaling_factor_rhoV = 1
  scaling_factor_rhouV = 1e-2
  scaling_factor_rhovV = 1e-2
  scaling_factor_rhowV = 1e-2
  scaling_factor_rhoEV = 1e-4
  closures = thm_closures
  fp = he
[]

[Functions]
  [m_dot_sec_fn]
    type = PiecewiseLinear
    xy_data = '
      0    0
      10 ${m_dot_sec_in}'
  []
[]

[FluidProperties]
  [he]
    type = IdealGasFluidProperties
    molar_mass = 4e-3
    gamma = 1.67
    k = 0.2556
    mu = 3.22639e-5
  []

  [water]
    type = StiffenedGasFluidProperties
    gamma = 2.35
    cv = 1816.0
    q = -1.167e6
    p_inf = 1.0e9
    q_prime = 0
  []
[]

[Closures]
  [thm_closures]
    type = Closures1PhaseTHM
  []
[]

[SolidProperties]
  [steel]
    type = ThermalFunctionSolidProperties
    rho = 8050
    k = 45
    cp = 466
  []
[]

[Components]
  [total_power]
    type = TotalPower
    power = ${tot_power}
  []
  [up_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 15
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct1]
    type = JunctionParallelChannels1Phase
    position = '0 0 0.5'
    connections = 'up_pipe_1:out core_chan:in'
    volume = 1e-5
    use_scalar_variables = false
  []
  [core_chan]
    type = FlowChannel1Phase
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    roughness = .0001
    A = ${A_core}
    D_h = ${Dh_core}
  []

  [core_hs]
    type = HeatStructureCylindrical
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    names = 'block'
    widths = '${fparse core_dia / 2.}'
    solid_properties = 'steel'
    solid_properties_T_ref = '300'
    n_part_elems = 3
  []

  [core_heating]
    type = HeatSourceFromTotalPower
    hs = core_hs
    regions = block
    power = total_power
  []

  [core_ht]
    type = HeatTransferFromHeatStructure1Phase
    flow_channel = core_chan
    hs = core_hs
    hs_side = outer
    P_hf = '${fparse pi * core_dia}'
  []

  [jct2]
    type = JunctionParallelChannels1Phase
    position = '0 0 1.5'
    connections = 'core_chan:out up_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [up_pipe_2]
    type = FlowChannel1Phase
    position = '0 0 1.5'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct3]
    type = JunctionOneToOne1Phase
    connections = 'up_pipe_2:out top_pipe_1:in'
  []

  [top_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [top_pipe_2]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '1 0 0'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct4]
    type = VolumeJunction1Phase
    position = '0.5 0 2'
    volume = 1e-5
    connections = 'top_pipe_1:out top_pipe_2:in press_pipe:in'
    use_scalar_variables = false
  []

  [press_pipe]
    type = FlowChannel1Phase
    position = '0.5 0 2'
    orientation = '0 1 0'
    length = 0.2
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pressurizer]
    type = InletStagnationPressureTemperature1Phase
    p0 = ${press}
    T0 = ${T_in}
    input = press_pipe:out
  []

  [jct5]
    type = JunctionOneToOne1Phase
    connections = 'top_pipe_2:out down_pipe_1:in'
  []

  [down_pipe_1]
    type = FlowChannel1Phase
    position = '1 0 2'
    orientation = '0 0 -1'
    length = 0.25
    A = ${A_pipe}
    n_elems = 5
  []

  [jct6]
    type = JunctionParallelChannels1Phase
    position = '1 0 1.75'
    connections = 'down_pipe_1:out hx/pri:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [hx]
    [pri]
      type = FlowChannel1Phase
      position = '1 0 1.75'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      roughness = 1e-5
      A = '${fparse pi * hx_dia_inner * hx_dia_inner / 4.}'
      D_h = ${hx_dia_inner}
    []

    [ht_pri]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = inner
      flow_channel = hx/pri
      P_hf = '${fparse pi * hx_dia_inner}'
    []

    [wall]
      type = HeatStructureCylindrical
      position = '1 0 1.75'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      widths = '${hx_wall_thickness}'
      n_part_elems = '3'
      solid_properties = 'steel'
      solid_properties_T_ref = '300'
      names = '0'
      inner_radius = '${fparse hx_dia_inner / 2.}'
    []

    [ht_sec]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = outer
      flow_channel = hx/sec
      P_hf = '${fparse 2 * pi * hx_radius_wall}'
    []

    [sec]
      type = FlowChannel1Phase
      position = '${fparse 1 + hx_wall_thickness} 0 0.25'
      orientation = '0 0 1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      A = '${fparse pi * (hx_dia_outer * hx_dia_outer / 4. - hx_radius_wall * hx_radius_wall)}'
      D_h = '${fparse hx_dia_outer - (2 * hx_radius_wall)}'
      fp = water
      initial_T = 300
    []
  []

  [jct7]
    type = JunctionParallelChannels1Phase
    position = '1 0 0.5'
    connections = 'hx/pri:out down_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [down_pipe_2]
    type = FlowChannel1Phase
    position = '1 0 0.25'
    orientation = '0 0 -1'
    length = 0.25
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct8]
    type = JunctionOneToOne1Phase
    connections = 'down_pipe_2:out bottom_1:in'
  []

  [bottom_1]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [pump]
    type = Pump1Phase
    position = '0.5 0 0'
    connections = 'bottom_1:out bottom_2:in'
    volume = 1e-4
    A_ref = ${A_pipe}
    head = 0
    use_scalar_variables = false
  []

  [bottom_2]
    type = FlowChannel1Phase
    position = '0.5 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct9]
    type = JunctionOneToOne1Phase
    connections = 'bottom_2:out up_pipe_1:in'
  []

  [inlet_sec]
    type = InletMassFlowRateTemperature1Phase
    input = 'hx/sec:in'
    m_dot = 0
    T = 300
  []

  [outlet_sec]
    type = Outlet1Phase
    input = 'hx/sec:out'
    p = 1e5
  []
[]

[ControlLogic]
  [set_point]
    type = GetFunctionValueControl
    function = ${m_dot_in}
  []

  [pid]
    type = PIDControl
    initial_value = 0.0
    set_point = set_point:value
    input = m_dot_pump
    K_p = 1.
    K_i = 4.
    K_d = 0
  []

  [set_pump_head]
    type = SetComponentRealValueControl
    component = pump
    parameter = head
    value = pid:output
  []

  [m_dot_sec_inlet_ctrl]
    type = GetFunctionValueControl
    function = m_dot_sec_fn
  []

  [set_m_dot_sec_ctrl]
    type = SetComponentRealValueControl
    component = inlet_sec
    parameter = m_dot
    value = m_dot_sec_inlet_ctrl:value
  []
[]

[Postprocessors]
  [power_to_coolant]
    type = ADHeatRateConvection1Phase
    block = core_chan
    P_hf = '${fparse pi *core_dia}'
  []

  [m_dot_pump]
    type = ADFlowJunctionFlux1Phase
    boundary = core_chan:in
    connection_index = 1
    equation = mass
    junction = jct7
  []

  [core_T_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = T
  []

  [core_p_in]
    type = SideAverageValue
    boundary = core_chan:in
    variable = p
  []

  [core_p_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = p
  []

  [core_delta_p]
    type = ParsedPostprocessor
    pp_names = 'core_p_in core_p_out'
    expression = 'core_p_in - core_p_out'
  []

  [hx_pri_T_out]
    type = SideAverageValue
    boundary = hx/pri:out
    variable = T
  []

  [hx_sec_T_in]
    type = SideAverageValue
    boundary = inlet_sec
    variable = T
  []

  [hx_sec_T_out]
    type = SideAverageValue
    boundary = outlet_sec
    variable = T
  []
  [m_dot_sec]
    type = ADFlowBoundaryFlux1Phase
    boundary = inlet_sec
    equation = mass
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  start_time = 0

  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1
  []
  dtmax = 5
  end_time = 500

  line_search = basic
  solve_type = NEWTON

  petsc_options_iname = '-pc_type'
  petsc_options_value = 'lu'

  nl_rel_tol = 0
  nl_abs_tol = 1e-8
  nl_max_its = 25

[]

[Outputs]
  exodus = true

  [console]
    type = Console
    max_rows = 1
    outlier_variable_norms = false
  []
  print_linear_residuals = false
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/conservation.i)

# Junction between 2 pipes where the second has half the area of the first.
# The momentum density of the second should be twice that of the first.

[GlobalParams]
  gravity_vector = '0 0 0'

  initial_T = 300
  initial_p = 1e5
  initial_vel = 20
  initial_vel_x = 20
  initial_vel_y = 0
  initial_vel_z = 0

  f = 0

  fp = eos

  scaling_factor_1phase = '1 1e-2 1e-5'
  scaling_factor_rhoEV = 1e-5

  closures = simple_closures
[]

[FluidProperties]
  [eos]
    type = StiffenedGasFluidProperties
    gamma = 1.4
    cv = 725
    p_inf = 0
    q = 0
    q_prime = 0
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Functions]
  [K_loss_fn]
    type = PiecewiseLinear
    x = '0 0.2'
    y = '0 1'
  []
[]

[Components]
  [pipe1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '1 0 0'
    length = 1
    A = 1
    n_elems = 20
  []

  [junction1]
    type = JunctionParallelChannels1Phase
    connections = 'pipe1:out pipe2:in'
    position = '1 0 0'
    volume = 1e-2
    K = 0
    use_scalar_variables = false
  []

  [pipe2]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '1 0 0'
    length = 1
    A = 0.5
    n_elems = 20
  []

  [junction2]
    type = JunctionParallelChannels1Phase
    connections = 'pipe2:out pipe1:in'
    position = '1 0 0'
    volume = 1e-2
    use_scalar_variables = false
  []
[]

[ControlLogic]
  active = ''
  [K_crtl]
    type = TimeFunctionComponentControl
    component = junction1
    parameter = K
    function = K_loss_fn
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  scheme = 'bdf2'

  start_time = 0
  dt = 0.05
  num_steps = 5
  abort_on_solve_fail = true

  solve_type = 'NEWTON'
  line_search = basic
  petsc_options_iname = '-pc_type'
  petsc_options_value = ' lu'
  nl_rel_tol = 0
  nl_abs_tol = 1e-8
  nl_max_its = 20

  l_tol = 1e-3
  l_max_its = 20

[]

[Postprocessors]
  # mass conservation
  [mass_pipes]
    type = ElementIntegralVariablePostprocessor
    variable = rhoA
    block = 'pipe1 pipe2'
    execute_on = 'initial timestep_end'
  []
  [mass_junction1]
    type = ElementAverageValue
    variable = rhoV
    block = 'junction1'
    execute_on = 'initial timestep_end'
  []
  [mass_junction2]
    type = ElementAverageValue
    variable = rhoV
    block = 'junction2'
    execute_on = 'initial timestep_end'
  []
  [mass_tot]
    type = SumPostprocessor
    values = 'mass_pipes mass_junction1 mass_junction2'
    execute_on = 'initial timestep_end'
  []
  [mass_tot_change]
    type = ChangeOverTimePostprocessor
    change_with_respect_to_initial = true
    postprocessor = mass_tot
    compute_relative_change = true
    execute_on = 'initial timestep_end'
  []

  # energy conservation
  [E_pipes]
    type = ElementIntegralVariablePostprocessor
    variable = rhoEA
    block = 'pipe1 pipe2'
    execute_on = 'initial timestep_end'
  []
  [E_junction1]
    type = ElementAverageValue
    variable = rhoEV
    block = 'junction1'
    execute_on = 'initial timestep_end'
  []
  [E_junction2]
    type = ElementAverageValue
    variable = rhoEV
    block = 'junction2'
    execute_on = 'initial timestep_end'
  []
  [E_tot]
    type = SumPostprocessor
    values = 'E_pipes E_junction1 E_junction2'
    execute_on = 'initial timestep_end'
  []
  [E_tot_change]
    type = ChangeOverTimePostprocessor
    change_with_respect_to_initial = true
    postprocessor = E_tot
    compute_relative_change = true
    execute_on = 'initial timestep_end'
  []

  [p_pipe1_out]
    type = SideAverageValue
    boundary = pipe1:out
    variable = p
  []
  [p_pipe2_in]
    type = SideAverageValue
    boundary = pipe2:in
    variable = p
  []
  [dp_junction]
    type = DifferencePostprocessor
    value1 = p_pipe1_out
    value2 = p_pipe2_in
  []
[]

[Outputs]
  [out]
    type = CSV
    show = 'mass_tot_change E_tot_change'
  []
[]

(modules/thermal_hydraulics/test/tests/components/junction_parallel_channels_1phase/equal_area_with_junction.i)

# Tests a junction between 2 flow channels of equal area and orientation. A
# sinusoidal density shape is advected to the right and should not be affected
# by the junction; the solution should be identical to the equivalent
# no-junction solution.

[GlobalParams]
  gravity_vector = '0 0 0'

  initial_p = 1e5
  initial_vel = 1

  A = 25

  f = 0

  fp = fp

  scaling_factor_1phase = '0.04 0.04 0.04e-5'

  closures = simple_closures
[]

[FluidProperties]
  [fp]
    type = StiffenedGasFluidProperties
    gamma = 1.4
    cv = 725
    p_inf = 0
    q = 0
    q_prime = 0
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[Functions]
  [T0]
    type = CosineHumpFunction
    axis = x
    hump_center_position = 1
    hump_width = 0.5
    hump_begin_value = 250
    hump_center_value = 300
  []
[]

[Components]
  [inlet]
    type = InletStagnationPressureTemperature1Phase
    input = 'pipe1:in'
    # Stagnation property with p = 1e5 Pa, T = 250 K, vel = 1 m/s
    p0 = 100000.68965687
    T0 = 250.00049261084
  []

  [pipe1]
    type = FlowChannel1Phase

    position = '0 0 0'
    orientation = '1 0 0'
    length = 1

    initial_T = T0

    n_elems = 25
  []

  [junction]
    type = JunctionParallelChannels1Phase
    connections = 'pipe1:out pipe2:in'

    position = '1.02 0 0'
    volume = 1.0

    initial_T = T0
    initial_vel_x = 1
    initial_vel_y = 0
    initial_vel_z = 0

    scaling_factor_rhoV  = 1
    scaling_factor_rhouV = 1
    scaling_factor_rhovV = 1
    scaling_factor_rhowV = 1
    scaling_factor_rhoEV = 1e-5

    use_scalar_variables = false
  []

  [pipe2]
    type = FlowChannel1Phase

    position = '1.04 0 0'
    orientation = '1 0 0'
    length = 0.96

    initial_T = T0

    n_elems = 24
  []

  [outlet]
    type = Outlet1Phase
    input = 'pipe2:out'
    p = 1e5
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient

  scheme = 'bdf2'
  start_time = 0
  dt = 0.01
  num_steps = 5
  abort_on_solve_fail = true

  solve_type = 'NEWTON'
  petsc_options_iname = '-pc_type'
  petsc_options_value = ' lu'
  line_search = 'basic'
  nl_rel_tol = 0
  nl_abs_tol = 1e-6
  nl_max_its = 10

  l_tol = 1e-3
  l_max_its = 10

  [Quadrature]
    type = GAUSS
    order = SECOND
  []
[]

[Postprocessors]
  [junction_rho]
    type = ElementAverageValue
    variable = rhoV
    block = 'junction'
    execute_on = 'initial timestep_end'
  []
  [junction_rhou]
    type = ElementAverageValue
    variable = rhouV
    block = 'junction'
    execute_on = 'initial timestep_end'
  []
  [junction_rhoE]
    type = ElementAverageValue
    variable = rhoEV
    block = 'junction'
    execute_on = 'initial timestep_end'
  []
[]

[Outputs]
  [out]
    type = CSV
    execute_scalars_on = 'none'
    execute_on = 'initial timestep_end'
  []
[]

(modules/thermal_hydraulics/tutorials/single_phase_flow/03_upper_loop.i)

T_in = 300. # K
m_dot_in = 1e-2 # kg/s
press = 10e5 # Pa

# core parameters
core_length = 1. # m
core_n_elems = 25
core_dia = '${units 2. cm -> m}'
core_pitch = '${units 8.7 cm -> m}'
A_core = '${fparse core_pitch^2 - 0.25 *pi * core_dia^2}'
P_wet_core = '${fparse 4*core_pitch + pi * core_dia}'
Dh_core = '${fparse 4 * A_core / P_wet_core}'

# pipe parameters
pipe_dia = '${units 10. cm -> m}'
A_pipe = '${fparse 0.25 * pi * pipe_dia^2}'

tot_power = 2000 # W

[GlobalParams]
  initial_p = ${press}
  initial_vel = 0.0001
  initial_T = ${T_in}
  initial_vel_x = 0
  initial_vel_y = 0
  initial_vel_z = 0
  gravity_vector = '0 0 0'

  rdg_slope_reconstruction = minmod
  scaling_factor_1phase = '1 1e-2 1e-4'
  scaling_factor_rhoV = 1
  scaling_factor_rhouV = 1e-2
  scaling_factor_rhovV = 1e-2
  scaling_factor_rhowV = 1e-2
  scaling_factor_rhoEV = 1e-4
  closures = thm_closures
  fp = he
[]

[FluidProperties]
  [he]
    type = IdealGasFluidProperties
    molar_mass = 4e-3
    gamma = 1.67
    k = 0.2556
    mu = 3.22639e-5
  []
[]

[Closures]
  [thm_closures]
    type = Closures1PhaseTHM
  []
[]

[SolidProperties]
  [steel]
    type = ThermalFunctionSolidProperties
    rho = 8050
    k = 45
    cp = 466
  []
[]

[Components]
  [total_power]
    type = TotalPower
    power = ${tot_power}
  []
  [inlet]
    type = InletMassFlowRateTemperature1Phase
    input = 'up_pipe_1:in'
    m_dot = ${m_dot_in}
    T = ${T_in}
  []

  [up_pipe_1]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 15
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct1]
    type = JunctionParallelChannels1Phase
    position = '0 0 0.5'
    connections = 'up_pipe_1:out core_chan:in'
    volume = 1e-5
    use_scalar_variables = false
  []
  [core_chan]
    type = FlowChannel1Phase
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    roughness = .0001
    A = '${A_core}'
    D_h = ${Dh_core}
  []

  [core_hs]
    type = HeatStructureCylindrical
    position = '0 0 0.5'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    names = 'block'
    widths = '${fparse core_dia / 2.}'
    solid_properties = 'steel'
    solid_properties_T_ref = '300'
    n_part_elems = 3
  []

  [core_heating]
    type = HeatSourceFromTotalPower
    hs = core_hs
    regions = block
    power = total_power
  []

  [core_ht]
    type = HeatTransferFromHeatStructure1Phase
    flow_channel = core_chan
    hs = core_hs
    hs_side = outer
    P_hf = '${fparse pi * core_dia}'
  []

  [jct2]
    type = JunctionParallelChannels1Phase
    position = '0 0 1.5'
    connections = 'core_chan:out up_pipe_2:in'
    volume = 1e-5
    use_scalar_variables = false
  []

  [up_pipe_2]
    type = FlowChannel1Phase
    position = '0 0 1.5'
    orientation = '0 0 1'
    length = 0.5
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct3]
    type = JunctionOneToOne1Phase
    connections = 'up_pipe_2:out top_pipe:in'
  []

  [top_pipe]
    type = FlowChannel1Phase
    position = '0 0 2'
    orientation = '1 0 0'
    length = 1
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [jct4]
    type = JunctionOneToOne1Phase
    connections = 'top_pipe:out down_pipe_1:in'
  []

  [down_pipe_1]
    type = FlowChannel1Phase
    position = '1 0 2'
    orientation = '0 0 -1'
    length = 0.25
    A = ${A_pipe}
    n_elems = 5
  []

  [jct5]
    type = JunctionOneToOne1Phase
    connections = 'down_pipe_1:out cooling_pipe:in'
  []

  [cooling_pipe]
    type = FlowChannel1Phase
    position = '1 0 1.75'
    orientation = '0 0 -1'
    length = 1.5
    n_elems = 25
    A = ${A_pipe}
  []

  [cold_wall]
    type = HeatTransferFromSpecifiedTemperature1Phase
    flow_channel = cooling_pipe
    T_wall = 300
    P_hf = '${fparse pi * pipe_dia}'
  []

  [jct6]
    type = JunctionOneToOne1Phase
    connections = 'cooling_pipe:out down_pipe_2:in'
  []

  [down_pipe_2]
    type = FlowChannel1Phase
    position = '1 0 0.25'
    orientation = '0 0 -1'
    length = 0.25
    n_elems = 10
    A = ${A_pipe}
    D_h = ${pipe_dia}
  []

  [outlet]
    type = Outlet1Phase
    input = 'down_pipe_2:out'
    p = ${press}
  []
[]

[Postprocessors]
  [power_to_coolant]
    type = ADHeatRateConvection1Phase
    block = core_chan
    P_hf = '${fparse pi *core_dia}'
  []

  [core_T_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = T
  []

  [core_p_in]
    type = SideAverageValue
    boundary = core_chan:in
    variable = p
  []

  [core_p_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = p
  []

  [core_delta_p]
    type = ParsedPostprocessor
    pp_names = 'core_p_in core_p_out'
    expression = 'core_p_in - core_p_out'
  []

  [hx_pri_T_out]
    type = SideAverageValue
    boundary = cooling_pipe:out
    variable = T
  []
[]

[Preconditioning]
  [pc]
    type = SMP
    full = true
  []
[]

[Executioner]
  type = Transient
  start_time = 0

  [TimeStepper]
    type = IterationAdaptiveDT
    dt = 1
  []
  end_time = 500

  line_search = basic
  solve_type = NEWTON

  petsc_options_iname = '-pc_type'
  petsc_options_value = 'lu'

  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-8
  nl_max_its = 25

[]

[Outputs]
  exodus = true

  [console]
    type = Console
    max_rows = 1
    outlier_variable_norms = false
  []
  print_linear_residuals = false
[]

(modules/thermal_hydraulics/include/components/SimpleTurbine1Phase.h)

// This file is part of the MOOSE framework
// https://www.mooseframework.org
//
// All rights reserved, see COPYRIGHT for full restrictions
// https://github.com/idaholab/moose/blob/master/COPYRIGHT
//
// Licensed under LGPL 2.1, please see LICENSE for details
// https://www.gnu.org/licenses/lgpl-2.1.html

#pragma once

#include "JunctionParallelChannels1Phase.h"

class SimpleTurbine1Phase;

/**
 * Simple turbine model that extracts prescribed power from the working fluid
 */
class SimpleTurbine1Phase : public JunctionParallelChannels1Phase
{
public:
  SimpleTurbine1Phase(const InputParameters & params);

  virtual void addVariables() override;
  virtual void addMooseObjects() override;

protected:
  virtual void buildVolumeJunctionUserObject() override;

  /// Flag that specifies if the turbine is operating or not
  const bool & _on;
  /// Turbine power [W]
  const Real & _power;
  /// Variable name that holds power
  VariableName _W_dot_var_name;

public:
  static InputParameters validParams();
};

Usage
Input Parameters
Formulation
Input Files
Child Objects
References