EquilibriumConstantAux Class Reference

Equilibrium constant (in the form log10(Keq)) calculated using a least-squares fit to the data provided (typically taken from a geochemical database). More...

#include <EquilibriumConstantAux.h>

Inheritance diagram for EquilibriumConstantAux:

Public Member Functions
	EquilibriumConstantAux (const InputParameters &parameters)

Protected Member Functions
virtual Real	computeValue () override

Protected Attributes
const VariableValue &	_temperature
	Temperature (in K) More...
const std::vector< Real > &	_temperature_points
	Temperature points in data set (in K) More...
const std::vector< Real > &	_logk_points
	log(Keq) values at each temperature point More...
std::unique_ptr< EquilibriumConstantFit >	_logk
	Least-squares fit to data. More...
std::unique_ptr< PolynomialFit >	_linear_logk
	Linear least-squares fit. More...

Detailed Description

Equilibrium constant (in the form log10(Keq)) calculated using a least-squares fit to the data provided (typically taken from a geochemical database).

Fitted function is a Maier-Kelly type function for the equilibrium constant

log10(Keq)= a_0 ln(T) + a_1 + a_2 T + a_3 / T + a_4 / T^2

where T is the temperature in Kelvin.

Note: At least 5 data values must be provided in order to use the Maier-Kelley fit. In some cases, insufficient data may be available. In these cases, the following fits are used instead:

If only one data point is available, log10(Keq) is set to a constant equal to the given point.

If between 2 and 4 data points are provided, a linear least squares fit is used.

Definition at line 41 of file EquilibriumConstantAux.h.

Constructor & Destructor Documentation

EquilibriumConstantAux()

EquilibriumConstantAux::EquilibriumConstantAux

(

const InputParameters &

parameters

)

Definition at line 30 of file EquilibriumConstantAux.C.

  : AuxKernel(parameters),
    _temperature(coupledValue("temperature")),
    _temperature_points(getParam<std::vector<Real>>("temperature_points")),
    _logk_points(getParam<std::vector<Real>>("logk_points"))
{
  // Check that the number of temperature_points and logk_points are equal
  if (_temperature_points.size() != _logk_points.size())
    mooseError("The number of temperature_points and logk_points must be equal in ", _name);
 
  if (_temperature_points.size() >= 5)
  {
    // If there at least 5 values, then use the Maier-Kelley fit
    _logk = libmesh_make_unique<EquilibriumConstantFit>(_temperature_points, _logk_points);
    _logk->generate();
  }
  else if ((_temperature_points.size() >= 2) && (_temperature_points.size() <= 4))
  {
    // If between 2 and 4 values are provided, use a linear fit
    _linear_logk = libmesh_make_unique<PolynomialFit>(_temperature_points, _logk_points, 1);
    _linear_logk->generate();
  }
}

Member Function Documentation

computeValue()

Real EquilibriumConstantAux::computeValue ( )

overrideprotectedvirtual

Definition at line 55 of file EquilibriumConstantAux.C.

{
  if (_temperature_points.size() == 1)
    return -_logk_points[0];
 
  if (_temperature_points.size() > 5)
    return -_logk->sample(_temperature[_qp]);
 
  return -_linear_logk->sample(_temperature[_qp]);
}

Member Data Documentation

_linear_logk

std::unique_ptr<PolynomialFit> EquilibriumConstantAux::_linear_logk

protected

Linear least-squares fit.

Definition at line 58 of file EquilibriumConstantAux.h.

Referenced by computeValue(), and EquilibriumConstantAux().

_logk

std::unique_ptr<EquilibriumConstantFit> EquilibriumConstantAux::_logk

protected

Least-squares fit to data.

Definition at line 56 of file EquilibriumConstantAux.h.

Referenced by computeValue(), and EquilibriumConstantAux().

_logk_points

const std::vector<Real>& EquilibriumConstantAux::_logk_points

protected

log(Keq) values at each temperature point

Definition at line 54 of file EquilibriumConstantAux.h.

Referenced by computeValue(), and EquilibriumConstantAux().

_temperature

const VariableValue& EquilibriumConstantAux::_temperature

protected

Temperature (in K)

Definition at line 50 of file EquilibriumConstantAux.h.

Referenced by computeValue().

_temperature_points

const std::vector<Real>& EquilibriumConstantAux::_temperature_points

protected

Temperature points in data set (in K)

Definition at line 52 of file EquilibriumConstantAux.h.

Referenced by computeValue(), and EquilibriumConstantAux().

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The documentation for this class was generated from the following files:

• chemical_reactions/include/auxkernels/EquilibriumConstantAux.h
• chemical_reactions/src/auxkernels/EquilibriumConstantAux.C