ChangeOverTimePostprocessor.C

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* 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

#include "ChangeOverTimePostprocessor.h"
#include "MooseUtils.h"

registerMooseObject("MooseApp", ChangeOverTimePostprocessor);

InputParameters
ChangeOverTimePostprocessor::validParams()
{
  InputParameters params = GeneralPostprocessor::validParams();

  params.addRequiredParam<PostprocessorName>("postprocessor", "The name of the postprocessor");
  params.addParam<bool>("change_with_respect_to_initial",
                        false,
                        "Compute change with respect to initial value instead of previous value");
  params.addParam<bool>(
      "compute_relative_change", false, "Compute magnitude of relative change instead of change");
  params.addParam<bool>("take_absolute_value", false, "Option to take absolute value of change");
  params.addParam<bool>("divide_by_dt",
                        false,
                        "If true, divide by the time step size. This may only be enabled if "
                        "'change_with_respect_to_initial' is 'false'.");

  params.addClassDescription("Computes the change or relative change in a post-processor value "
                             "over a timestep or the entire transient");

  return params;
}

ChangeOverTimePostprocessor::ChangeOverTimePostprocessor(const InputParameters & parameters)
  : GeneralPostprocessor(parameters),
    _change_with_respect_to_initial(getParam<bool>("change_with_respect_to_initial")),
    _compute_relative_change(getParam<bool>("compute_relative_change")),
    _take_absolute_value(getParam<bool>("take_absolute_value")),
    _divide_by_dt(getParam<bool>("divide_by_dt")),
    _pps_value(getPostprocessorValue("postprocessor")),
    _pps_value_old(getPostprocessorValueOld("postprocessor")),
    _pps_value_initial(declareRestartableData<Real>("pps_value_initial")),
    _value(0.0)
{
  if (_change_with_respect_to_initial)
  {
    // ensure dependent post-processor is executed on initial
    const PostprocessorName & pp_name = getParam<PostprocessorName>("postprocessor");
    const UserObject & pp = _fe_problem.getUserObject<UserObject>(pp_name);
    if (!pp.getExecuteOnEnum().isValueSet(EXEC_INITIAL))
      mooseError("When 'change_with_respect_to_initial' is specified to be true, 'execute_on' for "
                 "the dependent post-processor ('" +
                 pp_name + "') must include 'initial'");

    // ensure THIS post-processor is executed on initial
    if (!_execute_enum.isValueSet(EXEC_INITIAL))
      mooseError("When 'change_with_respect_to_initial' is specified to be true, 'execute_on' for "
                 "the ChangeOverTimePostprocessor ('" +
                 name() + "') must include 'initial'");

    // The quantity (y_n - y_{n-1})/dt_n has obvious physical relevance, but the
    // quantity (y_n - y_0)/dt_n has no obvious physical relevance, so we assume
    // that this is a mistake and do not allow it. This could be a warning instead if later needed.
    if (_divide_by_dt)
      mooseError(
          "The parameter 'divide_by_dt' may only be set to 'true' if "
          "'change_with_respect_to_initial' is 'false', since this is assumed to be unintended.");
  }
}

void
ChangeOverTimePostprocessor::initialize()
{
}

void
ChangeOverTimePostprocessor::execute()
{
}

void
ChangeOverTimePostprocessor::finalize()
{
  // copy initial value in case difference is measured against initial value
  if (_t_step == 0)
    _pps_value_initial = _pps_value;

  // determine value which change is measured against
  Real base_value;
  if (_change_with_respect_to_initial)
    base_value = _pps_value_initial;
  else
  {
    // Currently post-processors do not copy the values to old and older;
    // _pps_value_old will therefore always be zero for _t_step = 0.
    if (_t_step == 0)
      base_value = _pps_value;
    else
      base_value = _pps_value_old;
  }

  Real change;
  if (_compute_relative_change)
    change = (_pps_value - base_value) / base_value;
  else
    change = _pps_value - base_value;

  if (_take_absolute_value)
    _value = std::fabs(change);
  else
    _value = change;

  // Guard against division by zero; _dt=0 on INITIAL
  if (_divide_by_dt && !MooseUtils::absoluteFuzzyEqual(_dt, 0.0))
    _value /= _dt;
}

Real
ChangeOverTimePostprocessor::getValue() const
{
  return _value;
}