Detailed Description

Classes and functions used for calculating chemical equilibrium.

Classes
class	ChemEquil
	Class ChemEquil implements a chemical equilibrium solver for single-phase solutions. More...

class	MultiPhase
	A class for multiphase mixtures. More...

class	MultiPhaseEquil
	Multiphase chemical equilibrium solver. More...

class	vcs_MultiPhaseEquil
	Cantera's Interface to the Multiphase chemical equilibrium solver. More...

Functions
void	equilibrate (const string &XY, const string &solver="auto", double rtol=1e-9, int max_steps=50000, int max_iter=100, int estimate_equil=0, int log_level=0)
	Equilibrate a MultiPhase object.

size_t	BasisOptimize (int usedZeroedSpecies, bool doFormRxn, MultiPhase mphase, vector< size_t > &orderVectorSpecies, vector< size_t > &orderVectorElements, vector< double > &formRxnMatrix)
	Choose the optimum basis of species for the equilibrium calculations.

void	ElemRearrange (size_t nComponents, const vector< double > &elementAbundances, MultiPhase *mphase, vector< size_t > &orderVectorSpecies, vector< size_t > &orderVectorElements)
	Handles the potential rearrangement of the constraint equations represented by the Formula Matrix.

Chemical Equilibrium
Chemical equilibrium.
void	equilibrate (const string &XY, const string &solver="auto", double rtol=1e-9, int max_steps=50000, int max_iter=100, int estimate_equil=0, int log_level=0)
	Equilibrate a ThermoPhase object.

virtual void	setToEquilState (const double *mu_RT)
	This method is used by the ChemEquil equilibrium solver.

virtual bool	compatibleWithMultiPhase () const
	Indicates whether this phase type can be used with class MultiPhase for equilibrium calculations.

Function Documentation

◆ equilibrate() [1/2]

void equilibrate	(	const string &	XY,
		const string &	solver = `"auto"`,
		double	rtol = `1e-9`,
		int	max_steps = `50000`,
		int	max_iter = `100`,
		int	estimate_equil = `0`,
		int	log_level = `0`
	)

Equilibrate a MultiPhase object.

Set this mixture to chemical equilibrium by calling one of Cantera's equilibrium solvers. The XY parameter indicates what two thermodynamic quantities are to be held constant during the equilibration process.

Parameters

XY	String representation of what two properties are being held constant
solver	Name of the solver to be used to equilibrate the phase. If solver = 'vcs', the vcs_MultiPhaseEquil solver will be used. If solver = 'gibbs', the MultiPhaseEquil solver will be used. If solver = 'auto', the 'vcs' solver will be tried first, followed by the 'gibbs' solver if the first one fails.
rtol	Relative tolerance
max_steps	Maximum number of steps to take to find the solution
max_iter	The maximum number of outer temperature or pressure iterations to take when T and/or P is not held fixed.
estimate_equil	integer indicating whether the solver should estimate its own initial condition. If 0, the initial mole fraction vector in the ThermoPhase object is used as the initial condition. If 1, the initial mole fraction vector is used if the element abundances are satisfied. If -1, the initial mole fraction vector is thrown out, and an estimate is formulated.
log_level	loglevel Controls amount of diagnostic output. log_level=0 suppresses diagnostics, and increasingly-verbose messages are written as loglevel increases.

Definition at line 630 of file MultiPhase.cpp.

◆ BasisOptimize()

size_t BasisOptimize	(	int *	usedZeroedSpecies,
		bool	doFormRxn,
		MultiPhase *	mphase,
		vector< size_t > &	orderVectorSpecies,
		vector< size_t > &	orderVectorElements,
		vector< double > &	formRxnMatrix
	)

Choose the optimum basis of species for the equilibrium calculations.

This is done by choosing the species with the largest mole fraction not currently a linear combination of the previous components. Then, calculate the stoichiometric coefficient matrix for that basis.

Calculates the identity of the component species in the mechanism. Rearranges the solution data to put the component data at the front of the species list.

Then, calculates SC(J,I) the formation reactions for all noncomponent species in the mechanism.

Parameters

[in]	mphase	Pointer to the multiphase object. Contains the species mole fractions, which are used to pick the current optimal species component basis.
[in]	orderVectorElements	Order vector for the elements. The element rows in the formula matrix are rearranged according to this vector.
[in]	orderVectorSpecies	Order vector for the species. The species are rearranged according to this formula. The first nComponents of this vector contain the calculated species components on exit.
[in]	doFormRxn	If true, the routine calculates the formation reaction matrix based on the calculated component species. If false, this step is skipped.
[out]	usedZeroedSpecies	= If true, then a species with a zero concentration was used as a component. The problem may be converged.
[out]	formRxnMatrix

Returns: The number of components.

Definition at line 18 of file BasisOptimize.cpp.

◆ ElemRearrange()

void ElemRearrange	(	size_t	nComponents,
		const vector< double > &	elementAbundances,
		MultiPhase *	mphase,
		vector< size_t > &	orderVectorSpecies,
		vector< size_t > &	orderVectorElements
	)

Handles the potential rearrangement of the constraint equations represented by the Formula Matrix.

Rearrangement is only necessary when the number of components is less than the number of elements. For this case, some constraints can never be satisfied exactly, because the range space represented by the Formula Matrix of the components can't span the extra space. These constraints, which are out of the range space of the component Formula matrix entries, are migrated to the back of the Formula matrix.

A prototypical example is an extra element column in FormulaMatrix[], which is identically zero. For example, let's say that argon is has an element column in FormulaMatrix[], but no species in the mechanism actually contains argon. Then, nc < ne. Unless the entry for desired element abundance vector for Ar is zero, then this element abundance constraint can never be satisfied. The constraint vector is not in the range space of the formula matrix.

Also, without perturbation of FormulaMatrix[], BasisOptimize[] would produce a zero pivot because the matrix would be singular (unless the argon element column was already the last column of FormulaMatrix[].

This routine borrows heavily from BasisOptimize algorithm. It finds nc constraints which span the range space of the Component Formula matrix, and assigns them as the first nc components in the formula matrix. This guarantees that BasisOptimize has a nonsingular matrix to invert.

Parameters

[in]	nComponents	Number of components calculated previously.
[in]	elementAbundances	Current value of the element abundances
[in]	mphase	Input pointer to a MultiPhase object
[in]	orderVectorSpecies	input vector containing the ordering of the global species in mphase. This is used to extract the component basis of the mphase object.
[out]	orderVectorElements	Output vector containing the order of the elements that is necessary for calculation of the formula matrix.

Definition at line 292 of file BasisOptimize.cpp.

◆ equilibrate() [2/2]

void equilibrate	(	const string &	XY,
		const string &	solver = `"auto"`,
		double	rtol = `1e-9`,
		int	max_steps = `50000`,
		int	max_iter = `100`,
		int	estimate_equil = `0`,
		int	log_level = `0`
	)

Equilibrate a ThermoPhase object.

Set this phase to chemical equilibrium by calling one of several equilibrium solvers. The XY parameter indicates what two thermodynamic quantities are to be held constant during the equilibration process.

Parameters

XY	String representation of what two properties are being held constant
solver	Name of the solver to be used to equilibrate the phase. If solver = 'element_potential', the ChemEquil element potential solver will be used. If solver = 'vcs', the VCS solver will be used. If solver = 'gibbs', the MultiPhaseEquil solver will be used. If solver = 'auto', the solvers will be tried in order if the initial solver(s) fail.
rtol	Relative tolerance
max_steps	Maximum number of steps to take to find the solution
max_iter	For the 'gibbs' and 'vcs' solvers, this is the maximum number of outer temperature or pressure iterations to take when T and/or P is not held fixed.
estimate_equil	For MultiPhaseEquil solver, an integer indicating whether the solver should estimate its own initial condition. If 0, the initial mole fraction vector in the ThermoPhase object is used as the initial condition. If 1, the initial mole fraction vector is used if the element abundances are satisfied. If -1, the initial mole fraction vector is thrown out, and an estimate is formulated.
log_level	loglevel Controls amount of diagnostic output. log_level=0 suppresses diagnostics, and increasingly-verbose messages are written as loglevel increases.

Definition at line 1167 of file ThermoPhase.cpp.

◆ setToEquilState()

virtual void setToEquilState ( const double * mu_RT )

inlinevirtual

This method is used by the ChemEquil equilibrium solver.

It sets the state such that the chemical potentials satisfy

\[ \frac{\mu_k}{\hat R T} = \sum_m A_{k,m} \left(\frac{\lambda_m} {\hat R T}\right) \]

where \( \lambda_m \) is the element potential of element m. The temperature is unchanged. Any phase (ideal or not) that implements this method can be equilibrated by ChemEquil.

Parameters

mu_RT Input vector of dimensionless chemical potentials The length is equal to nSpecies().

Reimplemented in IdealSolnGasVPSS, IdealGasPhase, and IdealSolidSolnPhase.

Definition at line 1656 of file ThermoPhase.h.

◆ compatibleWithMultiPhase()

virtual bool compatibleWithMultiPhase ( ) const

inlinevirtual

Indicates whether this phase type can be used with class MultiPhase for equilibrium calculations.

Returns false for special phase types which already represent multi-phase mixtures, namely PureFluidPhase.

Reimplemented in PureFluidPhase, and WaterSSTP.

Definition at line 1663 of file ThermoPhase.h.

Detailed Description

Classes

Functions

Chemical Equilibrium

Function Documentation

◆ equilibrate() [1/2]

◆ BasisOptimize()

◆ ElemRearrange()

◆ equilibrate() [2/2]

◆ setToEquilState()

◆ compatibleWithMultiPhase()