PorousFlowSteadyStateTerminator

Returns 1 once a steady-state detection postprocessor falls below ss_relative_error (within the detection time window), or once ss_detection_end_time is reached, and 0 otherwise

Description

PorousFlowSteadyStateTerminator reports a 0/1 steady-state indicator, typically fed a detection metric produced by PorousFlowSteadyStateDetection. The reported value is 1 if either:

the current simulation time (timepostprocessor) is past ss_detection_start_time and targetpostprocessor is at or below ss_relative_error, or
the current simulation time is past ss_detection_end_time (regardless of targetpostprocessor, acting as a time-based fallback in case steady state is never detected);

and 0 otherwise.

This postprocessor only reports the indicator; it does not stop the simulation by itself. To actually terminate the run once steady state is detected, pair it with a Terminator [UserObjects] block whose expression tests this postprocessor's value, as shown in the example below.

Example Input Syntax

[Postprocessors<<<{"href": "../../syntax/Postprocessors/index.html"}>>>]
  [cur_time]
    type = TimePostprocessor<<<{"description": "Reports the current time", "href": "TimePostprocessor.html"}>>>
  []
  [target]
    type = FunctionValuePostprocessor<<<{"description": "Computes the value of a supplied function at a single point (scalable)", "href": "FunctionValuePostprocessor.html"}>>>
    function<<<{"description": "The function which supplies the postprocessor value."}>>> = target_fn
  []
  [computed]
    type = PorousFlowSteadyStateTerminator<<<{"description": "Returns 1 once a steady-state detection postprocessor falls below ss_relative_error (within the detection time window), or once ss_detection_end_time is reached, and 0 otherwise", "href": "PorousFlowSteadyStateTerminator.html"}>>>
    targetpostprocessor<<<{"description": "The name of the targetpostprocessor"}>>> = target
    timepostprocessor<<<{"description": "The name of the timepostprocessor"}>>> = cur_time
    ss_detection_start_time<<<{"description": "steady state detection start time"}>>> = 0
    ss_relative_error<<<{"description": "Postprocessor relative difference"}>>> = 0.2
  []
  [exact]
    type = FunctionValuePostprocessor<<<{"description": "Computes the value of a supplied function at a single point (scalable)", "href": "FunctionValuePostprocessor.html"}>>>
    function<<<{"description": "The function which supplies the postprocessor value."}>>> = exact_fn
  []
  [residual]
    type = ParsedPostprocessor<<<{"description": "Computes a parsed expression with post-processors", "href": "ParsedPostprocessor.html"}>>>
    pp_names<<<{"description": "Post-processors arguments"}>>> = 'computed exact'
    expression<<<{"description": "function expression"}>>> = 'abs(computed - exact)'
  []
[]

[UserObjects<<<{"href": "../../syntax/UserObjects/index.html"}>>>]
  [terminate]
    type = Terminator<<<{"description": "Requests termination of the current solve based on the evaluation of a parsed logical expression of the Postprocessor value(s).", "href": "../userobjects/Terminator.html"}>>>
    expression<<<{"description": "FParser expression to process Postprocessor values into a boolean value. Termination of the simulation occurs when this returns true."}>>> = 'computed >= 1'
  []
[]

Input Parameters

targetpostprocessorThe name of the targetpostprocessor
C++ Type:PostprocessorName
Unit:(no unit assumed)
Controllable:No
Description:The name of the targetpostprocessor
timepostprocessorThe name of the timepostprocessor
C++ Type:PostprocessorName
Unit:(no unit assumed)
Controllable:No
Description:The name of the timepostprocessor

Required Parameters

ss_detection_end_time1e+30steady state detection cap time
Default:1e+30
C++ Type:Real
Unit:(no unit assumed)
Controllable:No
Description:steady state detection cap time
ss_detection_start_time0steady state detection start time
Default:0
C++ Type:Real
Unit:(no unit assumed)
Controllable:No
Description:steady state detection start time
ss_relative_error0.01Postprocessor relative difference
Default:0.01
C++ Type:Real
Unit:(no unit assumed)
Controllable:No
Description:Postprocessor relative difference

Optional Parameters

allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Controllable:No
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Options:XFEM_MARK, NONE, INITIAL, LINEAR, LINEAR_CONVERGENCE, NONLINEAR, NONLINEAR_CONVERGENCE, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, MULTIAPP_FIXED_POINT_CONVERGENCE, MULTISYSTEM_FIXED_POINT_ITERATION_END, FINAL, CUSTOM, TRANSFER
Controllable:No
Description:The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
execution_order_group0Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
Default:0
C++ Type:int
Controllable:No
Description:Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
force_postauxFalseForces the UserObject to be executed in POSTAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in POSTAUX
force_preauxFalseForces the UserObject to be executed in PREAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREAUX
force_preicFalseForces the UserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup

Execution Scheduling Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
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
Controllable:Yes
Description:Set the enabled status of the MooseObject.
outputsVector of output names where you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector<OutputName>
Controllable:No
Description:Vector of output names where you would like to restrict the output of variables(s) associated with this object
use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Controllable:No
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

Advanced Parameters

prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Unit:(no unit assumed)
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

Material Property Retrieval Parameters

Input Files

(test/tests/postprocessors/porous_flow_steady_state_terminator/inp.i)
(test/tests/postprocessors/porous_flow_steady_state_detection/pair.i)

(test/tests/postprocessors/porous_flow_steady_state_terminator/inp.i)

# Analytic verification of PorousFlowSteadyStateTerminator, paired with a [UserObjects]
# Terminator to demonstrate that it can actually stop a run.
#
# PorousFlowSteadyStateTerminator::getValue() returns:
#   1 if (targetpostprocessor <= ss_relative_error AND timepostprocessor > ss_detection_start_time)
#        OR timepostprocessor > ss_detection_end_time
#   0 otherwise
#
# Drive targetpostprocessor(t) = 1/t (a synthetic, monotonically decreasing steady-state
# detection metric), ss_relative_error = 0.2, ss_detection_start_time = 0, and
# ss_detection_end_time left at its default (1.0e30, so it is never reached in this test,
# isolating the first OR branch) rather than set explicitly -- this exercises the actual class
# default directly: before it was fixed, the default was 0.0, which would have made the second
# OR branch fire unconditionally at t=1 regardless of ss_relative_error. dt = 1, num_steps = 8:
#
#   t=1: 1/1=1     >0.2 -> 0
#   t=2: 1/2=0.5   >0.2 -> 0
#   t=3: 1/3=0.333 >0.2 -> 0
#   t=4: 1/4=0.25  >0.2 -> 0
#   t=5: 1/5=0.2  <=0.2 -> 1   (first time the detection metric reaches the threshold)
#   t=6,7,8: 1/t  <=0.2 -> 1
#
# so exact(t) = if(t < 5, 0, 1).
#
# A [UserObjects] Terminator is paired on 'computed >= 1' with num_steps = 8, well past the t=5
# flip, so the run hard-stops right after the flip and the gold CSV has only 5 data rows (plus
# the initial row) instead of 8.

[Mesh/mesh]
  type = GeneratedMeshGenerator
  dim = 1
[]

[Problem]
  kernel_coverage_check = false
  solve = false
[]

[Functions]
  [target_fn]
    type = ParsedFunction
    expression = '1/t'
  []
  [exact_fn]
    type = ParsedFunction
    expression = 'if(t < 5, 0, 1)'
  []
[]

[Postprocessors]
  [cur_time]
    type = TimePostprocessor
  []
  [target]
    type = FunctionValuePostprocessor
    function = target_fn
  []
  [computed]
    type = PorousFlowSteadyStateTerminator
    targetpostprocessor = target
    timepostprocessor = cur_time
    ss_detection_start_time = 0
    ss_relative_error = 0.2
  []
  [exact]
    type = FunctionValuePostprocessor
    function = exact_fn
  []
  [residual]
    type = ParsedPostprocessor
    pp_names = 'computed exact'
    expression = 'abs(computed - exact)'
  []
[]

[UserObjects]
  [terminate]
    type = Terminator
    expression = 'computed >= 1'
  []
[]

[Executioner]
  type = Transient
  dt = 1
  num_steps = 8
[]

[Outputs]
  csv = true
[]

(test/tests/postprocessors/porous_flow_steady_state_terminator/inp.i)

# Analytic verification of PorousFlowSteadyStateTerminator, paired with a [UserObjects]
# Terminator to demonstrate that it can actually stop a run.
#
# PorousFlowSteadyStateTerminator::getValue() returns:
#   1 if (targetpostprocessor <= ss_relative_error AND timepostprocessor > ss_detection_start_time)
#        OR timepostprocessor > ss_detection_end_time
#   0 otherwise
#
# Drive targetpostprocessor(t) = 1/t (a synthetic, monotonically decreasing steady-state
# detection metric), ss_relative_error = 0.2, ss_detection_start_time = 0, and
# ss_detection_end_time left at its default (1.0e30, so it is never reached in this test,
# isolating the first OR branch) rather than set explicitly -- this exercises the actual class
# default directly: before it was fixed, the default was 0.0, which would have made the second
# OR branch fire unconditionally at t=1 regardless of ss_relative_error. dt = 1, num_steps = 8:
#
#   t=1: 1/1=1     >0.2 -> 0
#   t=2: 1/2=0.5   >0.2 -> 0
#   t=3: 1/3=0.333 >0.2 -> 0
#   t=4: 1/4=0.25  >0.2 -> 0
#   t=5: 1/5=0.2  <=0.2 -> 1   (first time the detection metric reaches the threshold)
#   t=6,7,8: 1/t  <=0.2 -> 1
#
# so exact(t) = if(t < 5, 0, 1).
#
# A [UserObjects] Terminator is paired on 'computed >= 1' with num_steps = 8, well past the t=5
# flip, so the run hard-stops right after the flip and the gold CSV has only 5 data rows (plus
# the initial row) instead of 8.

[Mesh/mesh]
  type = GeneratedMeshGenerator
  dim = 1
[]

[Problem]
  kernel_coverage_check = false
  solve = false
[]

[Functions]
  [target_fn]
    type = ParsedFunction
    expression = '1/t'
  []
  [exact_fn]
    type = ParsedFunction
    expression = 'if(t < 5, 0, 1)'
  []
[]

[Postprocessors]
  [cur_time]
    type = TimePostprocessor
  []
  [target]
    type = FunctionValuePostprocessor
    function = target_fn
  []
  [computed]
    type = PorousFlowSteadyStateTerminator
    targetpostprocessor = target
    timepostprocessor = cur_time
    ss_detection_start_time = 0
    ss_relative_error = 0.2
  []
  [exact]
    type = FunctionValuePostprocessor
    function = exact_fn
  []
  [residual]
    type = ParsedPostprocessor
    pp_names = 'computed exact'
    expression = 'abs(computed - exact)'
  []
[]

[UserObjects]
  [terminate]
    type = Terminator
    expression = 'computed >= 1'
  []
[]

[Executioner]
  type = Transient
  dt = 1
  num_steps = 8
[]

[Outputs]
  csv = true
[]

(test/tests/postprocessors/porous_flow_steady_state_terminator/inp.i)

# Analytic verification of PorousFlowSteadyStateTerminator, paired with a [UserObjects]
# Terminator to demonstrate that it can actually stop a run.
#
# PorousFlowSteadyStateTerminator::getValue() returns:
#   1 if (targetpostprocessor <= ss_relative_error AND timepostprocessor > ss_detection_start_time)
#        OR timepostprocessor > ss_detection_end_time
#   0 otherwise
#
# Drive targetpostprocessor(t) = 1/t (a synthetic, monotonically decreasing steady-state
# detection metric), ss_relative_error = 0.2, ss_detection_start_time = 0, and
# ss_detection_end_time left at its default (1.0e30, so it is never reached in this test,
# isolating the first OR branch) rather than set explicitly -- this exercises the actual class
# default directly: before it was fixed, the default was 0.0, which would have made the second
# OR branch fire unconditionally at t=1 regardless of ss_relative_error. dt = 1, num_steps = 8:
#
#   t=1: 1/1=1     >0.2 -> 0
#   t=2: 1/2=0.5   >0.2 -> 0
#   t=3: 1/3=0.333 >0.2 -> 0
#   t=4: 1/4=0.25  >0.2 -> 0
#   t=5: 1/5=0.2  <=0.2 -> 1   (first time the detection metric reaches the threshold)
#   t=6,7,8: 1/t  <=0.2 -> 1
#
# so exact(t) = if(t < 5, 0, 1).
#
# A [UserObjects] Terminator is paired on 'computed >= 1' with num_steps = 8, well past the t=5
# flip, so the run hard-stops right after the flip and the gold CSV has only 5 data rows (plus
# the initial row) instead of 8.

[Mesh/mesh]
  type = GeneratedMeshGenerator
  dim = 1
[]

[Problem]
  kernel_coverage_check = false
  solve = false
[]

[Functions]
  [target_fn]
    type = ParsedFunction
    expression = '1/t'
  []
  [exact_fn]
    type = ParsedFunction
    expression = 'if(t < 5, 0, 1)'
  []
[]

[Postprocessors]
  [cur_time]
    type = TimePostprocessor
  []
  [target]
    type = FunctionValuePostprocessor
    function = target_fn
  []
  [computed]
    type = PorousFlowSteadyStateTerminator
    targetpostprocessor = target
    timepostprocessor = cur_time
    ss_detection_start_time = 0
    ss_relative_error = 0.2
  []
  [exact]
    type = FunctionValuePostprocessor
    function = exact_fn
  []
  [residual]
    type = ParsedPostprocessor
    pp_names = 'computed exact'
    expression = 'abs(computed - exact)'
  []
[]

[UserObjects]
  [terminate]
    type = Terminator
    expression = 'computed >= 1'
  []
[]

[Executioner]
  type = Transient
  dt = 1
  num_steps = 8
[]

[Outputs]
  csv = true
[]

(test/tests/postprocessors/porous_flow_steady_state_detection/pair.i)

# Regression test for PorousFlowSteadyStateDetection wired to PorousFlowSteadyStateTerminator --
# the pairing both doc pages recommend, and which no single input exercised before.
#
# PorousFlowSteadyStateDetection cannot compute a relative rate of change on the first timestep
# (TimestepSize's "old" value is 0 there), nor whenever the target's old value is 0 (the normal
# state of a cumulative or integral quantity at t0). For those cases it reports a large sentinel,
# 1e30.
#
# It must NOT report 0. The terminator below treats a SMALL value as converged, so with its default
# ss_relative_error = 1e-2 and ss_detection_start_time = 0, a 0 would satisfy
#   value <= ss_relative_error && t > ss_detection_start_time
# on the very first step, and the Terminator UserObject would hard-stop the run one step in --
# reporting an instantly-converged steady state. Both parameters are deliberately left at their
# defaults here, because it is the defaults that make that the observable failure.
#
# The target is deliberately far from steady: target(t) = 5 + t gives a relative rate of change of
# 1/(4 + t), which is still 0.1 at the last step -- an order of magnitude above ss_relative_error.
# The terminator must therefore never fire and the run must reach all 6 steps.
#
# If the sentinel ever regresses to 0, the Terminator fires at t = 1, the CSV is truncated, and
# CSVDiff's row-count check turns that into a failure.

[Mesh/mesh]
  type = GeneratedMeshGenerator
  dim = 1
[]

[Problem]
  kernel_coverage_check = false
  solve = false
[]

[Functions]
  [target_fn]
    type = ParsedFunction
    expression = '5 + t'
  []
[]

[Postprocessors]
  [dt_pp]
    type = TimestepSize
    execute_on = 'initial timestep_end'
  []
  [cur_time]
    type = TimePostprocessor
  []
  [target]
    type = FunctionValuePostprocessor
    function = target_fn
    execute_on = 'initial timestep_end'
  []
  [ss_detect]
    type = PorousFlowSteadyStateDetection
    targetpostprocessor = target
    dt_postprocessor = dt_pp
  []
  [ss_term]
    type = PorousFlowSteadyStateTerminator
    targetpostprocessor = ss_detect
    timepostprocessor = cur_time
    # ss_relative_error, ss_detection_start_time and ss_detection_end_time all left at defaults.
  []
[]

[UserObjects]
  [terminate_on_steady_state]
    type = Terminator
    expression = 'ss_term > 0.5'
    message = 'PorousFlowSteadyStateTerminator reported steady state'
  []
[]

[Executioner]
  type = Transient
  dt = 1
  num_steps = 6
[]

[Outputs]
  csv = true
[]

Description
Example Input Syntax
Input Parameters
Input Files

Theory

Usage

Development

PorousFlowSteadyStateTerminator

Description

Example Input Syntax

Input Parameters

Required Parameters

Optional Parameters

Execution Scheduling Parameters

Advanced Parameters

Material Property Retrieval Parameters

Input Files