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DRGEP< CompType, ThermoType > Class Template Reference

The DRGEP algorithm [1] is based on. More...

Inheritance diagram for DRGEP< CompType, ThermoType >:
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Collaboration diagram for DRGEP< CompType, ThermoType >:
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Public Member Functions

TypeName ("DRGEP")
Runtime type information. More...

DRGEP (const IOdictionary &dict, TDACChemistryModel< CompType, ThermoType > &chemistry)
Construct from components. More...

virtual ~DRGEP ()
Destructor. More...

virtual void reduceMechanism (const scalarField &c, const scalar T, const scalar p)
Reduce the mechanism. More...

Public Member Functions inherited from chemistryReductionMethod< CompType, ThermoType >
TypeName ("chemistryReductionMethod")
Runtime type information. More...

declareRunTimeSelectionTable (autoPtr, chemistryReductionMethod, dictionary,(const IOdictionary &dict, TDACChemistryModel< CompType, ThermoType > &chemistry),(dict, chemistry))

chemistryReductionMethod (const IOdictionary &dict, TDACChemistryModel< CompType, ThermoType > &chemistry)
Construct from components. More...

virtual ~chemistryReductionMethod ()
Destructor. More...

bool active () const
Is mechanism reduction active? More...

bool log () const
Is performance data logging enabled? More...

const List< bool > & activeSpecies () const
Return the active species. More...

label NsSimp ()
Return the number of active species. More...

label nSpecie ()
Return the initial number of species. More...

scalar tolerance () const
Return the tolerance. More...

virtual void reduceMechanism (const scalarField &c, const scalar T, const scalar p)=0
Reduce the mechanism. More...

Static Public Member Functions inherited from chemistryReductionMethod< CompType, ThermoType >
static autoPtr< chemistryReductionMethod< CompType, ThermoType > > New (const IOdictionary &dict, TDACChemistryModel< CompType, ThermoType > &chemistry)

Protected Attributes inherited from chemistryReductionMethod< CompType, ThermoType >
const IOdictionarydict_

const dictionary coeffsDict_
Dictionary that store the algorithm data. More...

Switch active_
Is mechanism reduction active? More...

Switch log_
Switch to select performance logging. More...

TDACChemistryModel< CompType, ThermoType > & chemistry_

List< boolactiveSpecies_
List of active species (active = true) More...

label NsSimp_
Number of active species. More...

const label nSpecie_
Number of species. More...

scalar tolerance_
Tolerance for the mechanism reduction algorithm. More...

Detailed Description

template<class CompType, class ThermoType>
class Foam::chemistryReductionMethods::DRGEP< CompType, ThermoType >

The DRGEP algorithm [1] is based on.

|sum_i=1->Nr vAi wi dBi| rAB = ————————— , max(PA, CA)

PA = sum_i=1->Nr (max (0, vAi wi)) -> production of species A

CA = sum_i=1->Nr (max (0, -vAi wi)) -> consumption of species A

where i is the reaction index, Nr the number of reactions, vAi is the net stoechiometric coefficient of species A in the ith reaction (vAi = v''-v') , wi is the progress variable of reaction i and dBi equals 1 if reaction i involves B and O otherwise. rAB show the error introduced to the production rates of A when B and all the reactions including it are removed. It is computed as in [2] so that the algorithm is O(Nr).

DAC uses a initial set of species that represents the major parts of the combustion mechanism, i.e. H2/O2, fuel decomposition and CO2 production. Usually, it includes the fuel, HO2 and CO. Then it computes the dependence of these set to the other species. This is done by introducing R-value defined by

R_V0 (V) = max_SP(product(rij)) ,

where SP is the set of all possible paths leading from V0 to V and product(rij) is the chain product of the weights of the edges along the given path. The R-value for the initial set species is 1.

When the R-value of a species is larger than a user-defined tolerance then the species is included in the simplified mechanism. Otherwise, the species is removed along with all the reactions including it.

During this process, instead of looking over all species like described in [1], the algorithm implemented here creates dynamic list to retain the initialized edges only (see [2]).

To avoid using the target species when they are not contributing yet or anymore to the system, a coefficient based on the exchange of element is introduced:

NTa |PT - CT| alphaTa = —————- Pa

Pa = sum_speciesS NSa max(0, PS-CS)

where 'a' refers to different elements present in the system (namely C, H, O and N for conventionail hydrocarbon combustion), NTa is the number of element a in species T. When this coefficient alpha is below the specified threshold, the species is removed from the search initiating set. In the original paper from Pepiot-Desjardins et al.[2], this coefficient is further transformed to compute a global normalized scaling coefficient but here as it is dynamically computed, alpha is not introduced in the calculation of R.

References:

    [1] Pepiot-Desjardins, P., & Pitsch, H. (2008).
An efficient error-propagation-based reduction method for large
chemical kinetic mechanisms.
Combustion and Flame, 154(1), 67-81.

[2] Lu, T., & Law, C. K. (2006).
Linear time reduction of large kinetic mechanisms with directed
relation graph: n-Heptane and iso-octane.
Combustion and Flame, 144(1), 24-36.

Source files

Definition at line 121 of file DRGEP.H.

◆ DRGEP()

 DRGEP ( const IOdictionary & dict, TDACChemistryModel< CompType, ThermoType > & chemistry )

Construct from components.

Definition at line 34 of file DRGEP.C.

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◆ ~DRGEP()

 virtual

Destructor.

Definition at line 106 of file DRGEP.C.

◆ TypeName()

 TypeName ( "DRGEP< CompType, ThermoType >" )

Runtime type information.

◆ reduceMechanism()

 void reduceMechanism ( const scalarField & c, const scalar T, const scalar p )
virtual

Reduce the mechanism.

Definition at line 113 of file DRGEP.C.

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The documentation for this class was generated from the following files:
• src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DRGEP/DRGEP.H
• src/thermophysicalModels/chemistryModel/chemistryModel/TDACChemistryModel/reduction/DRGEP/DRGEP.C