== ORCh background ==
ORCh (Optimised and Reduced Chemistry) is a fully automated method to reduce detailed chemical schemes. This page describes the architecture of the method and explains how to install and run ORCh.

The development of ORCh is reported in two archival papers (make sure to cite those papers when using this program):
* N. Jaouen, L. Vervisch, P. Domingo, G. Ribert (2017) Automatic reduction and optimisation of chemistry for turbulent combustion modeling: Impact of the canonical problem, Combust. Flame, 175: 60-79.
* N. Jaouen, L. Vervisch, P. Domingo (2017) Auto-thermal reforming (ATR) of natural gas: An automated derivation of optimised reduced chemical schemes, Proc. Combust. Inst., 36(3): 3321-3330.

ORCh has been applied to various reactive flow problems:

* K. Bioche, G. Ribert, L. Vervisch (2019) Simulating upstream flame propagation in a narrow channel after wall preheating: Flame analysis and chemistry reduction strategy, Combust. Flame. 200: 219-231.
* C. Locci, L. Vervisch, B. Farcy, P. Domingo, N. Perret (2018) Selective Non-Catalytic Reduction (SNCR) of nitrogen oxide emissions: A perspective from numerical modeling, Flow Turbulence and Combust. 100(2): 301-340.
* K. Bioche, L. Vervisch, G. Ribert (2018) Premixed flame-wall interaction in a narrow channel: Impact of wall thermal conductivity and heat losses, J. Fluid Mech. 856: 5-35
* A. Bouaniche, N. Jaouen, P. Domingo, L. Vervisch (in press) Vitiated high Karlovitz n-decane/air turbulent flames: Scaling laws and micro-mixing modeling analysis, Flow Turbulence and Combust

ORCh is a preprocessing tool designed to automatically generate and optimise reduced chemistry for specific CFD conditions, including fuel spray, heat losses, etc.

ORCh combines stochastic methods with graph-analysis together with genetic algorithms

Written in C++ it comes with a user friendly interface

Most recent and on-going applications
* Furnaces with Urea DeNOx
* High-pressure partial oxydation of methane (hydrogen production)
* Combustion in narrow channels with wall heat losses (micro- and meso-scale combustion, fire propagation between battery cells)
* Heavy hydrocarbon liquid fuel (kerosene surrogate or pyrolyse)
* Chlorofluorocarbon chemistry
* Soot precursors
* Coal combustion
* Combustion of blast furnace gases

=== Architecture of the method ===

[[File:diagram_global.jpg]]

* [[Cantera]]

* [[Optimisation]]

* [[Lumping]]

* [[Directed Relation Graph with Error Propagation (DRGEP)]]

* [[Read_write]]

* [[Tools]]

* [[Main]]

* [[Chemical kinetics]]

* [[Quasi-Steady State analysis]]

Tools

* [[Gnuplot]]

* [[Linux]]

* [[Latex]]

=== User guide ===

* [[orch:Installation Guide]]

* [[Inputs]]

* [[Outputs]]

=== Test cases ===

* [[Premix CH_4/Air flame with scheme GRI12]]

* [[Multi-inlet CH_4/Air flame with scheme GRI12]]

* [[Auto-ignition CH_4/Air flame with scheme GRI12]]

[[File:diagram_test.png|800px|]]

Main Page

2019-07-16T13:10:14Z

Seltz: /* User guide */

== ORCh background ==
ORCh (Optimised and Reduced Chemistry) is a fully automated method to reduce detailed chemical schemes. This page describes the architecture of the method and explains how to install and run ORCh.

The development of ORCh is reported in two archival papers (make sure to cite those papers when using this program):
* N. Jaouen, L. Vervisch, P. Domingo, G. Ribert (2017) Automatic reduction and optimisation of chemistry for turbulent combustion modeling: Impact of the canonical problem, Combust. Flame, 175: 60-79.
* N. Jaouen, L. Vervisch, P. Domingo (2017) Auto-thermal reforming (ATR) of natural gas: An automated derivation of optimised reduced chemical schemes, Proc. Combust. Inst., 36(3): 3321-3330.

ORCh has been applied to various reactive flow problems:

* K. Bioche, G. Ribert, L. Vervisch (2019) Simulating upstream flame propagation in a narrow channel after wall preheating: Flame analysis and chemistry reduction strategy, Combust. Flame. 200: 219-231.
* C. Locci, L. Vervisch, B. Farcy, P. Domingo, N. Perret (2018) Selective Non-Catalytic Reduction (SNCR) of nitrogen oxide emissions: A perspective from numerical modeling, Flow Turbulence and Combust. 100(2): 301-340.
* K. Bioche, L. Vervisch, G. Ribert (2018) Premixed flame-wall interaction in a narrow channel: Impact of wall thermal conductivity and heat losses, J. Fluid Mech. 856: 5-35
* A. Bouaniche, N. Jaouen, P. Domingo, L. Vervisch (in press) Vitiated high Karlovitz n-decane/air turbulent flames: Scaling laws and micro-mixing modeling analysis, Flow Turbulence and Combust

ORCh is a preprocessing tool designed to automatically generate and optimise reduced chemistry for specific CFD conditions, including fuel spray, heat losses, etc.

ORCh combines stochastic methods with graph-analysis together with genetic algorithms

Written in C++ it comes with a user friendly interface

Most recent and on-going applications
* Furnaces with Urea DeNOx
* High-pressure partial oxydation of methane (hydrogen production)
* Combustion in narrow channels with wall heat losses (micro- and meso-scale combustion, fire propagation between battery cells)
* Heavy hydrocarbon liquid fuel (kerosene surrogate or pyrolyse)
* Chlorofluorocarbon chemistry
* Soot precursors
* Coal combustion
* Combustion of blast furnace gases

=== Architecture of the method ===

[[File:diagram_global.jpg]]

* [[Cantera]]

* [[Optimisation]]

* [[Lumping]]

* [[Directed Relation Graph with Error Propagation (DRGEP)]]

* [[Read_write]]

* [[Tools]]

* [[Main]]

* [[Chemical kinetics]]

* [[Quasi-Steady State analysis]]

Tools

* [[Gnuplot]]

* [[Linux]]

* [[Latex]]

=== User guide ===

* [[Installation]]

* [[Inputs]]

* [[Outputs]]

=== Test cases ===

* [[Premix CH_4/Air flame with scheme GRI12]]

* [[Multi-inlet CH_4/Air flame with scheme GRI12]]

* [[Auto-ignition CH_4/Air flame with scheme GRI12]]

[[File:diagram_test.png|800px|]]

Installation Guide

2019-07-16T13:05:41Z

Seltz: Created blank page

Main Page

2019-07-16T13:05:05Z

Seltz: /* User guide */

== ORCh background ==
ORCh (Optimised and Reduced Chemistry) is a fully automated method to reduce detailed chemical schemes. This page describes the architecture of the method and explains how to install and run ORCh.

The development of ORCh is reported in two archival papers (make sure to cite those papers when using this program):
* N. Jaouen, L. Vervisch, P. Domingo, G. Ribert (2017) Automatic reduction and optimisation of chemistry for turbulent combustion modeling: Impact of the canonical problem, Combust. Flame, 175: 60-79.
* N. Jaouen, L. Vervisch, P. Domingo (2017) Auto-thermal reforming (ATR) of natural gas: An automated derivation of optimised reduced chemical schemes, Proc. Combust. Inst., 36(3): 3321-3330.

ORCh has been applied to various reactive flow problems:

* K. Bioche, G. Ribert, L. Vervisch (2019) Simulating upstream flame propagation in a narrow channel after wall preheating: Flame analysis and chemistry reduction strategy, Combust. Flame. 200: 219-231.
* C. Locci, L. Vervisch, B. Farcy, P. Domingo, N. Perret (2018) Selective Non-Catalytic Reduction (SNCR) of nitrogen oxide emissions: A perspective from numerical modeling, Flow Turbulence and Combust. 100(2): 301-340.
* K. Bioche, L. Vervisch, G. Ribert (2018) Premixed flame-wall interaction in a narrow channel: Impact of wall thermal conductivity and heat losses, J. Fluid Mech. 856: 5-35
* A. Bouaniche, N. Jaouen, P. Domingo, L. Vervisch (in press) Vitiated high Karlovitz n-decane/air turbulent flames: Scaling laws and micro-mixing modeling analysis, Flow Turbulence and Combust

ORCh is a preprocessing tool designed to automatically generate and optimise reduced chemistry for specific CFD conditions, including fuel spray, heat losses, etc.

ORCh combines stochastic methods with graph-analysis together with genetic algorithms

Written in C++ it comes with a user friendly interface

Most recent and on-going applications
* Furnaces with Urea DeNOx
* High-pressure partial oxydation of methane (hydrogen production)
* Combustion in narrow channels with wall heat losses (micro- and meso-scale combustion, fire propagation between battery cells)
* Heavy hydrocarbon liquid fuel (kerosene surrogate or pyrolyse)
* Chlorofluorocarbon chemistry
* Soot precursors
* Coal combustion
* Combustion of blast furnace gases

=== Architecture of the method ===

[[File:diagram_global.jpg]]

* [[Cantera]]

* [[Optimisation]]

* [[Lumping]]

* [[Directed Relation Graph with Error Propagation (DRGEP)]]

* [[Read_write]]

* [[Tools]]

* [[Main]]

* [[Chemical kinetics]]

* [[Quasi-Steady State analysis]]

Tools

* [[Gnuplot]]

* [[Linux]]

* [[Latex]]

=== User guide ===

* [[Installation Guide]]

* [[Inputs]]

* [[Outputs]]

=== Test cases ===

* [[Premix CH_4/Air flame with scheme GRI12]]

* [[Multi-inlet CH_4/Air flame with scheme GRI12]]

* [[Auto-ignition CH_4/Air flame with scheme GRI12]]

[[File:diagram_test.png|800px|]]

orch:Installation Guide

2019-07-16T13:04:23Z

Seltz:

=== Pre installation ===

The 2.4 version of Cantera needs C++ Boost librairies (Version 1.68, the newer don't work with Cantera) to run properly.

... patience ... the boost installation can be long

Moreover, the cantera sources can be built with scons.

MPI librairies will be also needed for Stochastic configurations.

=== Installation procedure ===

The installation location should follow a given format. As the path to the orch folder must follow:

<code>
./workdir/orch$
</code>

The orch repository should be positioned in a workdir folder. So create the workdir folder in which you clone the orch repository from the gitlab:

<code>
/home/user/workdir$ git clone git@gitlab.coria-cfd.fr:orch/orch.git
</code>

The gt_comb folder, in which is placed cantera must be at the same level than the workdir folder, so as to say in the previous example:

<code>
/home/user/gt_comb/cantera$
</code>

== Installation ==
The following steps must be completed before you can use ORCh:
* Compile Cantera :
with the compiler SCONS
command : scons build
be sure to add the right paths to boost when the first error message shows up

* Add to your .bashrc file:
<code>export GTCOMB_CT_HOME=/home/yourloggin/orch/Cantera</code>
<code>export GTCOMB_CT_HOSTTYPE=$GTCOMB_CT_HOME/lib</code>
<code>export GTCOMB_CT_DATA=$GTCOMB_CT_HOME/data</code>

* All the openmpi and gcc-compiler libraries must be available on your machine, typically you need something like below in your .bashrc file (some may already be there no need to duplicate):
<code>source /opt/intel/composerxe/bin/compilervars.sh intel64</code>
<code>export INTEL_HOME="/opt/intel/composerxe"</code>
<code>export INTEL_INC="$INTEL_HOME/include"</code>
<code>export INTEL_LIB="$INTEL_HOME/lib"</code>
<code>export INTEL_BIN="$INTEL_HOME/bin"</code>
<code>export INTEL_MAN="$INTEL_HOME/man"</code>
<code>export PATH="$INTEL_BIN:$PATH"</code>
<code>export LIBRARY_PATH="$INTEL_LIB:$LIBRARY_PATH"</code>
<code>export LD_LIBRARY_PATH="$INTEL_LIB:$LD_LIBRARY_PATH"</code>
<code>export MANPATH="$INTEL_MAN:$MANPATH"</code>

<code>export MPI_HOME="/local/openmpi/intel-14.0.2/1.8.1"</code>
<code>export MPI_INC="$MPI_HOME/include"</code>
<code>export MPI_LIB="$MPI_HOME/lib"</code>
<code>export MPI_BIN="$MPI_HOME/bin"</code>
<code>export MPI_MAN="$MPI_HOME/share/man"</code>
<code>export PATH="$MPI_BIN:$PATH"</code>
<code>export LIBRARY_PATH="$MPI_LIB:$LIBRARY_PATH"</code>
<code>export LD_LIBRARY_PATH="$MPI_LIB:$LD_LIBRARY_PATH"</code>
<code>export MANPATH="$MPI_MAN:$MANPATH"</code>

<code>export HDF5_HOME="/local/hdf5/intel-14.0.2/1.8.12"</code>
<code>export HDF5_INC="$HDF5_HOME/include"</code>
<code>export HDF5_BIN="$HDF5_HOME/bin"</code>
<code>export HDF5_LIB="$HDF5_HOME/lib"</code>
<code>export PATH="$HDF5_BIN:$PATH"</code>
<code>export LIBRARY_PATH="$HDF5_LIB:$LIBRARY_PATH"</code>
<code>export LD_LIBRARY_PATH="$HDF5_LIB:$LD_LIBRARY_PATH"</code>

<code>export PAPI_HOME="/local/papi/intel-14.0.2/5.3.0"</code>
<code>export LANG=C</code>
<code>export LC_ALL=C</code>
<code>export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:/usr/include/x86_64-linux-gnu/c++/4.8</code>

* Check that the compilation of the ORCh package runs fine
<code> make clean </code>
<code> make </code>

2019-02-01T13:21:26Z

Seltz: /* General keywords */

=== General keywords ===

All the necessary key words are contained in the file "input_file.ini", this is where you specify the characteristics of your flame and the ORCh step you want to run.

First, you choose the studied combustion regime (premixed flame, auto-ignition ou multiple Inlet regime) with the key word "configuration".

Then, the ORCh step you want to perform ([[DRGEP|DRGEP_species]], DRGEP_reactions, ComputeTrajectories, computeQSSCriteria, getQSSfile, getQSSfileFORTRAN, Optimisation, or Lumping) with the key word "step".

The reference chemical scheme (key word mech_ref) (by default it is the scheme "mech" from which the user begins the step) and his associated trajectory file (key word : trajectory_ref) are optional.

Note that mech_ref and trajectory_ref are optional and useful only if the user wants to plot and calculate the fitness with other reference schemes than the default one. To use the default one, put "mech_ref = None"

The reference scheme (mech) of the current step, and the mechanism description (mech_desc) (the mech_desc doesn't change through the ORCh steps and corresponds to the id of the mechanism) :

The level of debug wanted (generally 1)

The species trajectories and/or the temperature and the flame speed (in Premixed configuration) the user wants to vizualise during the step (key word speciesToPlot).

Also if you want to plot the temperature and the flame velocity :
plot_T = 1 or 0 //temperature plot
plot_U = 1 or 0 //flame speed plot

Then you define your target species with the key word "Target".

=== Premixed flame ===

If you want to reduce schemes for premixed flames, firstly you will run a flame with the following inputs :

configuration = "PremixedFlames";

listFlames.push_back(new PremixedFlames( fuel temperature, oxider temperature, pressure, ratio, Yf, Xf, Yo, Xo, path of the reference flame, path of the new flame));

In order to converge faster, you have to indicate a reference flame with characteristics close to the ones you want to run.

Note that you can perform the steps on several premixed flames, by adding more flames and the associated reference trajectories in the same order.

listFlames.push_back(...)
listFlames.push_back(...)
...

trajectory_ref.push_back("");
trajectory_ref.push_back("");
...

=== Multiple Inlet ===

Concerning this regime, as many inlets as needed can be added with the following characteristics :

//Inlet i
listInlets.push_back(new MultipleInlet(
"Temperature",
"Pressure",
"Mass flow rate",
"Xk",
"Yk",
/*evaporationModel*/ true or false,
/*DropletDiameter*/,
/*Tau_vj (characteristic time of evaporation)*/,
/*liquidDensity*/,
/*EvaporationlatentHeat*/));

Coupled with the inlet of burned gases :

//BurnedGases
listInlets.push_back(new MultipleInlet(
"Temperature",
"Pressure",
"Mass flow rate",
"Xk",
"Yk",
/*evaporationModel*/ false,
/*DropletDiameter*/0.0,
/*Tau_vj (characteristic time of evaporation)*/0.0,
/*liquidDensity*/0.0,
/*EvaporationlatentHeat*/ 0.0,
/*tau_t (mixing time)*/,
/*delta_t (time step)*/0.0,
/*nbIterations*/0.0,
/*BurnedGases*/ true ));

One last parameter is necessary :

new_mixing = "true or false"

which determine if the mixing of the fluid particles is new or set from a previous mixing. For the first step of the analysis, this parameter is set to true, and false for all the other steps of the study, so the random mixing of the first step is re-used for the other ones.

=== QSS and optimisation key words ===

Concerning the QSS part, the user have to fill a vector with the species put in QSS assumption. The user can test several scenarios (definition of multiple vectors)

//------QSS Scenarios------//

string array1[17] {"species1", "species2"};
vector<string> vec(array1, array1 + sizeof(array1) /sizeof(array1[0]));
listQSSscenarios.push_back(new QSSscenario(vec));

...

For the optimisation step, the user must indicate the size of the population at each generation, the number of generation that will be calculated, the number of the best solutions to copy generation to generation, the cross and mutation rate (best let to 0.75 and 0.02) and finally the allowed variation on the Arrhenius factors.

//------Optimisation------//

//MAKE SURE THE "listQSSscenarios" THAT IS PUSHED FIRST, IS THE SCENARIO YOU WANT TO OPTIMISE

int PopSize = 22;
int MaxAllowableGenerations = 10;
int NbElitism = 1;

double CrossoverRate = 0.75;
double MutationRate = 0.02;

double AllowedVariation_A = 0.005;
double AllowedVariation_b = 0;
double AllowedVariation_E = 0;

listOptimScenarios = new OptimScenario(PopSize, MaxAllowableGenerations, NbElitism, CrossoverRate, MutationRate, AllowedVariation_A, AllowedVariation_b, AllowedVariation_E);

File:Optim PremixGRI12.png

2019-02-01T13:11:57Z

Seltz: Seltz uploaded a new version of File:Optim PremixGRI12.png

Premix CH 4/Air flame with scheme GRI12

2019-02-01T13:07:26Z

Seltz: /* Optimisation */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below (part of the input_file.ini) :

//------Flame parameters------//
//Flame 0
Tf = 300
To = 300
Pressure = 1E+05
Equivalence_ratio = 0.75
Xf = CH4:1.0
Xo = O2:0.21, N2:0.79
// the composition can also be added with mass fractions, for that replace "Xf" by "Yf" and "Xo" by "Yo"
Initial_flame = flames/flame__Phi_0_75__P_100000__T_300.cantera
Final_flame = flames/flame
//End

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

MECHANISM:------------------------------------------------------------------------------------------------------
Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177

PREMIXED FLAME:--------------------------------------------------------------
Reading initial flame "flames/flame__Phi_0_75__P_100000__T_300.cantera" with description "st_flame" ----------> description: test flame
OK
Pressure: 100000
Equivalence ratio: 0.75
Composition (mass fractions):
<O2:0.223145>
<CH4:0.0419532>
<N2:0.734901>

followed by the the species associated with their rank :

-------DRGEP coefficients-------
--------------------------------
1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

We can note that the main target profiles are not impacted by the QSS hypothesis, nevertheless the fitness seems better. This is due to errors compensations by the other species not shown here (remind that the fitness is calculated for all species, velocity and temperature, the target just have a larger impact coefficient on the fitness).

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 40 elements was used during 50 generations.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

Premix CH 4/Air flame with scheme GRI12

2019-02-01T10:16:01Z

Seltz: /* QSS step */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below (part of the input_file.ini) :

//------Flame parameters------//
//Flame 0
Tf = 300
To = 300
Pressure = 1E+05
Equivalence_ratio = 0.75
Xf = CH4:1.0
Xo = O2:0.21, N2:0.79
// the composition can also be added with mass fractions, for that replace "Xf" by "Yf" and "Xo" by "Yo"
Initial_flame = flames/flame__Phi_0_75__P_100000__T_300.cantera
Final_flame = flames/flame
//End

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

MECHANISM:------------------------------------------------------------------------------------------------------
Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177

PREMIXED FLAME:--------------------------------------------------------------
Reading initial flame "flames/flame__Phi_0_75__P_100000__T_300.cantera" with description "st_flame" ----------> description: test flame
OK
Pressure: 100000
Equivalence ratio: 0.75
Composition (mass fractions):
<O2:0.223145>
<CH4:0.0419532>
<N2:0.734901>

followed by the the species associated with their rank :

-------DRGEP coefficients-------
--------------------------------
1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

We can note that the main target profiles are not impacted by the QSS hypothesis, nevertheless the fitness seems better. This is due to errors compensations by the other species not shown here (remind that the fitness is calculated for all species, velocity and temperature, the target just have a larger impact coefficient on the fitness).

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

File:QSS 12sp Premixed.png

2019-02-01T10:09:40Z

Seltz: Seltz uploaded a new version of File:QSS 12sp Premixed.png

Multi-inlet CH 4/Air flame with scheme GRI12

2019-01-31T15:59:22Z

Seltz: /* DRGEP Step */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 0D 2-inlet configuration. Starting with 32 species and 177 reactions, we reduce to 12 transported species, 2 species in quasi steady state assumption and 28 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. We are at atmospheric pressure, and the fuel is injected in its gaseous form (no evaporation model). The inputs of the 3 inlets (oxidiser, fuel and burned gases) are displayed below (from the input_file.ini):

//------Inlets------//
new Inlet 0 : Air
T = 700
Pressure = 1E+05
MassFlowRate = 0.500
Xk = O2:0.21, N2:0.79
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = false
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0
//EndInlet

new Inlet 1 : Fuel
T = 450
Pressure = 1E+05
MassFlowRate = 0.017
Xk = CH4:1.0
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = 0
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0
//EndInlet

new Inlet : GB
T = 2500
Pressure = 1E+05
MassFlowRate = 0.2
Xk = N2:0.76308, O2:0.093573, H2O:0.072355, CO2:0.070468
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = 0 ///1 to activate the model
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0

== '''Results''' ==

=== DRGEP Step ===

While running the DRGEP species step, your terminal should display the following information :

MECHANISM:------------------------------------------------------------------------------------------------------
Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177

Composition to enter For the equilibrium computation to get the Burned gases
Compo_H_mixed 525637
X_O2: 0.16931
X_H2O: 0.019848
X_CH4: 0.0418227
X_CO2: 0.0193304
X_N2: 0.749689
T_mixed 1212.8
Nb particles 0 500
Nb particles 1 17
Nb particles 2 200
Nmix 35
Set the mole fraction of inlet 0
Set the mole fraction of inlet 1
Set the mole fraction of inlet 2

followed by the the species associated with their rank :

0 AR
1.41837e-05 HCCOH
0.000287651 C
0.000489111 CH2CO
0.000498049 C2H
0.00327403 C2H2
0.00356528 CH2OH
0.00476023 CH
0.00528262 HCCO
0.0119242 H2O2
0.0130846 C2H3
0.0164568 CH3OH
0.0358106 C2H4
0.0358106 C2H5
0.0380984 CH2(S)
0.0394904 CH2
0.0692651 H2
0.120645 C2H6
0.144271 HCO
0.146106 CH2O
0.193431 CH3O
0.345988 O
0.699261 H
0.699262 OH
0.999998 HO2
0.999999 CH3
1 O2
1 H2O
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 11 species). and we choose the one with 14 species for the next step. With 13 species and less, the trajectories of the targets and the temperature are too different from the detailed ones to be easily optimised.

[[File:14sp_42R.png|600px|center]]

Fig1 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions (in red) for the fuel inlet.

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank. The global reactions are displayed below :

Reaction 11 7.11815e-05
Reaction 2 9.22955e-05
Reaction 1 9.5273e-05
Reaction 18 0.002098
Reaction 31 0.00268202
Reaction 10 0.00415073
Reaction 6 0.00453937
Reaction 12 0.0058625
Reaction 22 0.00631152
Reaction 7 0.0107781
Reaction 8 0.0107783
Reaction 34 0.0154049
Reaction 19 0.0177938
Reaction 29 0.0220001
Reaction 25 0.0269477
Reaction 24 0.0322283
Reaction 37 0.0341651
Reaction 40 0.0553785
Reaction 9 0.0611019
Reaction 32 0.0701004
Reaction 39 0.0765675
Reaction 38 0.148919
Reaction 35 0.164745
Reaction 3 0.165682
Reaction 14 0.166509
Reaction 30 0.173203
Reaction 23 0.250228
Reaction 21 0.364056
Reaction 36 0.459012
Reaction 26 0.491301
Reaction 5 0.494067
Reaction 28 0.550285
Reaction 20 0.606395
Reaction 42 0.607008
Reaction 15 0.736774
Reaction 17 0.754281
Reaction 16 0.791332
Reaction 41 0.855392
Reaction 33 0.948061
Reaction 13 0.969153
Reaction 4 0.974258
Reaction 27 0.992507

After this step, by comparing the reference trajectories with the new ones, we choose to delete 13 reactions, so the next step is performed with 14 species and 28 reactions. Indeed, with 27 and less species, the final state of the trajectories is not well predicted and difficult to represent even with the optimisation step.

[[File:14sp_28R.png|600px|center]]

Fig2 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 28 reactions (in red) for the fuel inlet.

=== QSS Step ===

While running the QSS step, your terminal should display the following information :

Species H 0.00794323
Species O 0.00490131
Species O2 1
Species OH 0.00320187
Species H2O 0.0582805
Species HO2 0.012535
Species CH3 0.0853549
Species CH4 0.794206
Species CO 1
Species CO2 1
Species HCO 0.00362124
Species CH2O 0.181152
Species CH3O 0.00472456
Species N2 1

Interactions with species H with QSS Criteria 0.00794323
H2O:2 HO2:1 CH3:1 CH2O:2 CH3O:1

Interactions with species O with QSS Criteria 0.00490131
OH:1 H2O:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.00320187
O:1 OH:2 HO2:1 CH3:2 HCO:1 CH2O:2 CH3O:1

Interactions with species H2O with QSS Criteria 0.0582805
H:2 O:1 HO2:1 CH3:1 HCO:2

Interactions with species HO2 with QSS Criteria 0.012535
H:1 O:1 OH:1 H2O:1 CH3:2 CH2O:1

Interactions with species CH3 with QSS Criteria 0.0853549
H:1 O:1 OH:2 H2O:1 HO2:2 HCO:1 CH2O:1

Interactions with species HCO with QSS Criteria 0.00362124
OH:1 H2O:2 CH3:1

Interactions with species CH2O with QSS Criteria 0.181152
H:2 O:1 OH:2 HO2:1 CH3:1

Interactions with species CH3O with QSS Criteria 0.00472456
H:1 O:1 OH:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient.

In order to obtain the trajectories of the 12-transported species 28-reactions reduced scheme, we run the getQSSfile step and we observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:12sp_28R.png|600px|center]]

Fig3 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 28 reactions (in red) for the fuel inlet.

=== Optimisation Step ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. We allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 40 elements was used during 40 generations.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 28 reactions.

[[File:optim_stoch_GRI.png|600px|center]]

Fig4 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 28 reactions (in red) after optimisation for the fuel inlet.

Multi-inlet CH 4/Air flame with scheme GRI12

2019-01-31T15:53:15Z

Seltz: /* Key parameters */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 0D 2-inlet configuration. Starting with 32 species and 177 reactions, we reduce to 12 transported species, 2 species in quasi steady state assumption and 28 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. We are at atmospheric pressure, and the fuel is injected in its gaseous form (no evaporation model). The inputs of the 3 inlets (oxidiser, fuel and burned gases) are displayed below (from the input_file.ini):

//------Inlets------//
new Inlet 0 : Air
T = 700
Pressure = 1E+05
MassFlowRate = 0.500
Xk = O2:0.21, N2:0.79
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = false
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0
//EndInlet

new Inlet 1 : Fuel
T = 450
Pressure = 1E+05
MassFlowRate = 0.017
Xk = CH4:1.0
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = 0
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0
//EndInlet

new Inlet : GB
T = 2500
Pressure = 1E+05
MassFlowRate = 0.2
Xk = N2:0.76308, O2:0.093573, H2O:0.072355, CO2:0.070468
// the composition can also be added with molar fractions, for that replace "Yk" by "Xk"
EvaporationModel = 0 ///1 to activate the model
DropletDiameter = 0.0
EvaporationTime = 0.0
liquidDensity = 0.0
EvaporationLatentHeat = 0.0

== '''Results''' ==

=== DRGEP Step ===

While running the DRGEP species step, your terminal should display the following information :

Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177
Set the mole fraction of inlet 0
Set the mole fraction of inlet 1
Set the mole fraction of inlet 2

Composition to enter For the equilibrium computation to get the Burned gases
Compo_H_mixed 525637
X_O2: 0.16931
X_H2O: 0.019848
X_CH4: 0.0418227
X_CO2: 0.0193304
X_N2: 0.749689
T_mixed 1212.8
Nb particles 0 500
Nb particles 1 17
Nb particles 2 200
Nmix 35
Set the mole fraction of inlet 0
Set the mole fraction of inlet 1
Set the mole fraction of inlet 2

followed by the the species associated with their rank :

0 AR
1.41837e-05 HCCOH
0.000287651 C
0.000489111 CH2CO
0.000498049 C2H
0.00327403 C2H2
0.00356528 CH2OH
0.00476023 CH
0.00528262 HCCO
0.0119242 H2O2
0.0130846 C2H3
0.0164568 CH3OH
0.0358106 C2H4
0.0358106 C2H5
0.0380984 CH2(S)
0.0394904 CH2
0.0692651 H2
0.120645 C2H6
0.144271 HCO
0.146106 CH2O
0.193431 CH3O
0.345988 O
0.699261 H
0.699262 OH
0.999998 HO2
0.999999 CH3
1 O2
1 H2O
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 11 species). and we choose the one with 14 species for the next step. With 13 species and less, the trajectories of the targets and the temperature are too different from the detailed ones to be easily optimised.

[[File:14sp_42R.png|600px|center]]

Fig1 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions (in red) for the fuel inlet.

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank. The global reactions are displayed below :

Reaction 11 7.11815e-05
Reaction 2 9.22955e-05
Reaction 1 9.5273e-05
Reaction 18 0.002098
Reaction 31 0.00268202
Reaction 10 0.00415073
Reaction 6 0.00453937
Reaction 12 0.0058625
Reaction 22 0.00631152
Reaction 7 0.0107781
Reaction 8 0.0107783
Reaction 34 0.0154049
Reaction 19 0.0177938
Reaction 29 0.0220001
Reaction 25 0.0269477
Reaction 24 0.0322283
Reaction 37 0.0341651
Reaction 40 0.0553785
Reaction 9 0.0611019
Reaction 32 0.0701004
Reaction 39 0.0765675
Reaction 38 0.148919
Reaction 35 0.164745
Reaction 3 0.165682
Reaction 14 0.166509
Reaction 30 0.173203
Reaction 23 0.250228
Reaction 21 0.364056
Reaction 36 0.459012
Reaction 26 0.491301
Reaction 5 0.494067
Reaction 28 0.550285
Reaction 20 0.606395
Reaction 42 0.607008
Reaction 15 0.736774
Reaction 17 0.754281
Reaction 16 0.791332
Reaction 41 0.855392
Reaction 33 0.948061
Reaction 13 0.969153
Reaction 4 0.974258
Reaction 27 0.992507

After this step, by comparing the reference trajectories with the new ones, we choose to delete 13 reactions, so the next step is performed with 14 species and 28 reactions. Indeed, with 27 and less species, the final state of the trajectories is not well predicted and difficult to represent even with the optimisation step.

[[File:14sp_28R.png|600px|center]]

Fig2 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 28 reactions (in red) for the fuel inlet.

=== QSS Step ===

While running the QSS step, your terminal should display the following information :

Species H 0.00794323
Species O 0.00490131
Species O2 1
Species OH 0.00320187
Species H2O 0.0582805
Species HO2 0.012535
Species CH3 0.0853549
Species CH4 0.794206
Species CO 1
Species CO2 1
Species HCO 0.00362124
Species CH2O 0.181152
Species CH3O 0.00472456
Species N2 1

Interactions with species H with QSS Criteria 0.00794323
H2O:2 HO2:1 CH3:1 CH2O:2 CH3O:1

Interactions with species O with QSS Criteria 0.00490131
OH:1 H2O:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.00320187
O:1 OH:2 HO2:1 CH3:2 HCO:1 CH2O:2 CH3O:1

Interactions with species H2O with QSS Criteria 0.0582805
H:2 O:1 HO2:1 CH3:1 HCO:2

Interactions with species HO2 with QSS Criteria 0.012535
H:1 O:1 OH:1 H2O:1 CH3:2 CH2O:1

Interactions with species CH3 with QSS Criteria 0.0853549
H:1 O:1 OH:2 H2O:1 HO2:2 HCO:1 CH2O:1

Interactions with species HCO with QSS Criteria 0.00362124
OH:1 H2O:2 CH3:1

Interactions with species CH2O with QSS Criteria 0.181152
H:2 O:1 OH:2 HO2:1 CH3:1

Interactions with species CH3O with QSS Criteria 0.00472456
H:1 O:1 OH:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient.

In order to obtain the trajectories of the 12-transported species 28-reactions reduced scheme, we run the getQSSfile step and we observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:12sp_28R.png|600px|center]]

Fig3 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 28 reactions (in red) for the fuel inlet.

=== Optimisation Step ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. We allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 40 elements was used during 40 generations.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 28 reactions.

[[File:optim_stoch_GRI.png|600px|center]]

Fig4 : Comparison between the reference trajectories of the target species and the temperature (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 28 reactions (in red) after optimisation for the fuel inlet.

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:50:36Z

Seltz: /* Key parameters */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below (part of the input_file.ini) :

//------Flame parameters------//
//Flame 0
Tf = 300
To = 300
Pressure = 1E+05
Equivalence_ratio = 0.75
Xf = CH4:1.0
Xo = O2:0.21, N2:0.79
// the composition can also be added with mass fractions, for that replace "Xf" by "Yf" and "Xo" by "Yo"
Initial_flame = flames/flame__Phi_0_75__P_100000__T_300.cantera
Final_flame = flames/flame
//End

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

MECHANISM:------------------------------------------------------------------------------------------------------
Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177

PREMIXED FLAME:--------------------------------------------------------------
Reading initial flame "flames/flame__Phi_0_75__P_100000__T_300.cantera" with description "st_flame" ----------> description: test flame
OK
Pressure: 100000
Equivalence ratio: 0.75
Composition (mass fractions):
<O2:0.223145>
<CH4:0.0419532>
<N2:0.734901>

followed by the the species associated with their rank :

-------DRGEP coefficients-------
--------------------------------
1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:46:47Z

Seltz: /* DRGEP step */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below :

//------Flame parameters------//
//Flame 0
Tf = 300
To = 300
Pressure = 1E+05
Equivalence_ratio = 0.75
Xf = CH4:1.0
Xo = O2:0.21, N2:0.79
// the composition can also be added with mass fractions, for that replace "Xf" by "Yf" and "Xo" by "Yo"
Initial_flame = flames/flame__Phi_0_75__P_100000__T_300.cantera
Final_flame = flames/flame
//End

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

MECHANISM:------------------------------------------------------------------------------------------------------
Reading initial mechanism "mechanisms/gri12.xml" with description "gri12" ----------> OK
Number of species: 32
Number of reactions: 177

PREMIXED FLAME:--------------------------------------------------------------
Reading initial flame "flames/flame__Phi_0_75__P_100000__T_300.cantera" with description "st_flame" ----------> description: test flame
OK
Pressure: 100000
Equivalence ratio: 0.75
Composition (mass fractions):
<O2:0.223145>
<CH4:0.0419532>
<N2:0.734901>

followed by the the species associated with their rank :

-------DRGEP coefficients-------
--------------------------------
1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:41:13Z

Seltz: /* Key parameters */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below :

//------Flame parameters------//
//Flame 0
Tf = 300
To = 300
Pressure = 1E+05
Equivalence_ratio = 0.75
Xf = CH4:1.0
Xo = O2:0.21, N2:0.79
// the composition can also be added with mass fractions, for that replace "Xf" by "Yf" and "Xo" by "Yo"
Initial_flame = flames/flame__Phi_0_75__P_100000__T_300.cantera
Final_flame = flames/flame
//End

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

scheme : GRI12
number of species : 32
number of reaction : 177
reference flame : flames/flame__Phi_0_75__P_100000__T_300.cantera
Pressure : 1 bar
equivalence ration : 0.75
Composition : <O2:0.202024>
<CH4:0.0379821>
<N2:0.759994>

followed by the the species associated with their rank :

1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:24:13Z

Seltz: /* QSS step */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below :

listFlames.push_back(new PremixedFlames(/*T_fuel*/ 300,
/*T_ox*/ 300,
/*Pressure*/ 1E+05,
/*Ratio*/ 0.75,
/*Y_fuel*/ "CH4:1.0",
/*X_fuel*/ "",
/*Y_ox*/ "O2:0.21, N2:0.79",
/*X_ox*/ "",
/*reference_flame_path*/ "flames/flame__Phi_0_75__P_100000__T_300.cantera",
/*flame_path*/ "flames/flame"));

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

scheme : GRI12
number of species : 32
number of reaction : 177
reference flame : flames/flame__Phi_0_75__P_100000__T_300.cantera
Pressure : 1 bar
equivalence ration : 0.75
Composition : <O2:0.202024>
<CH4:0.0379821>
<N2:0.759994>

followed by the the species associated with their rank :

1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0752034
Species O 0.0211171
Species O2 0.33194
Species OH 0.019287
Species H2O 0.379235
Species HO2 0.0113201
Species CH3 0.107792
Species CH4 0.79541
Species CO 0.693792
Species CO2 0.720209
Species HCO 0.00321461
Species CH2O 0.0817911
Species CH3O 0.0360026
Species N2 0

Interactions with species H with QSS Criteria 0.0752034
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0211171
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.019287
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.0113201
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.107792
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00321461
OH:2

Interactions with species CH2O with QSS Criteria 0.0817911
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0360026
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:22:08Z

Seltz: /* Results */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below :

listFlames.push_back(new PremixedFlames(/*T_fuel*/ 300,
/*T_ox*/ 300,
/*Pressure*/ 1E+05,
/*Ratio*/ 0.75,
/*Y_fuel*/ "CH4:1.0",
/*X_fuel*/ "",
/*Y_ox*/ "O2:0.21, N2:0.79",
/*X_ox*/ "",
/*reference_flame_path*/ "flames/flame__Phi_0_75__P_100000__T_300.cantera",
/*flame_path*/ "flames/flame"));

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

scheme : GRI12
number of species : 32
number of reaction : 177
reference flame : flames/flame__Phi_0_75__P_100000__T_300.cantera
Pressure : 1 bar
equivalence ration : 0.75
Composition : <O2:0.202024>
<CH4:0.0379821>
<N2:0.759994>

followed by the the species associated with their rank :

1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 22 9.23227e-06
Reaction 1 2.08238e-05
Reaction 11 2.29985e-05
Reaction 2 5.30076e-05
Reaction 12 0.00029274
Reaction 18 0.00191785
Reaction 6 0.00198407
Reaction 36 0.00293471
Reaction 38 0.00420356
Reaction 31 0.00462285
Reaction 34 0.00611017
Reaction 7 0.00905302
Reaction 10 0.00921383
Reaction 32 0.0106164
Reaction 37 0.0133867
Reaction 8 0.0136681
Reaction 25 0.0237175
Reaction 24 0.0277978
Reaction 29 0.0305413
Reaction 13 0.0329515
Reaction 9 0.0342601
Reaction 3 0.0398655
Reaction 5 0.0422524
Reaction 14 0.0442348
Reaction 19 0.0493222
Reaction 35 0.102885
Reaction 40 0.103946
Reaction 26 0.111933
Reaction 30 0.131232
Reaction 23 0.159996
Reaction 21 0.161005
Reaction 20 0.180048
Reaction 39 0.18465
Reaction 42 0.19675
Reaction 4 0.208145
Reaction 15 0.215404
Reaction 16 0.222982
Reaction 27 0.274358
Reaction 17 0.274617
Reaction 33 0.403162
Reaction 41 0.437888
Reaction 28 0.438952

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0581710482364302
Species O 0.0160759870785582
Species O2 0.277560360139677
Species OH 0.0144373005142915
Species H2O 0.314791474636433
Species HO2 0.010252726793236
Species CH3 0.100336627880574
Species CH4 0.79524736833312
Species CO 0.694064507028327
Species CO2 0.692897407440143
Species HCO 0.00243878401227475
Species CH2O 0.0772557856780877
Species CH3O 0.0207969879289909
Species N2 0

Interactions with species H with QSS Criteria 0.0581710482364302
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0160759870785582
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.0144373005142915
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.010252726793236
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.100336627880574
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00243878401227475
OH:2

Interactions with species CH2O with QSS Criteria 0.0772557856780877
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0207969879289909
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

File:DRGEPR 14sp 26R Premixed.png

2019-01-31T15:17:16Z

Seltz: Seltz uploaded a new version of File:DRGEPR 14sp 26R Premixed.png

Premix CH 4/Air flame with scheme GRI12

2019-01-31T15:12:36Z

Seltz: /* DRGEP step */

== '''Objectives''' ==

The Stochastic_GRI12 test case describes a reduction of the GRI1.2 scheme for a 1D premixed flame. Starting with 32 species and 177 reactions, we reduce to 14 species and 26 reactions.

== '''Key parameters''' ==

The target species considered for this test case are O2, CO and CO2. The characteristics of the premixed flame are displayed below :

listFlames.push_back(new PremixedFlames(/*T_fuel*/ 300,
/*T_ox*/ 300,
/*Pressure*/ 1E+05,
/*Ratio*/ 0.75,
/*Y_fuel*/ "CH4:1.0",
/*X_fuel*/ "",
/*Y_ox*/ "O2:0.21, N2:0.79",
/*X_ox*/ "",
/*reference_flame_path*/ "flames/flame__Phi_0_75__P_100000__T_300.cantera",
/*flame_path*/ "flames/flame"));

== '''Results''' ==

=== DRGEP step ===

While running the DRGEP species step, your terminal should display the following information :

scheme : GRI12
number of species : 32
number of reaction : 177
reference flame : flames/flame__Phi_0_75__P_100000__T_300.cantera
Pressure : 1 bar
equivalence ration : 0.75
Composition : <O2:0.202024>
<CH4:0.0379821>
<N2:0.759994>

followed by the the species associated with their rank :

1.37642e-15 AR
2.12795e-06 HCCOH
4.32935e-05 C2H
0.000157543 CH2CO
0.000362521 C
0.000444401 C2H2
0.00101888 HCCO
0.00357515 C2H3
0.00398744 CH3OH
0.00409277 CH
0.00543294 CH2OH
0.0126485 C2H4
0.0126485 C2H5
0.0170844 CH2(S)
0.0190984 C2H6
0.0314311 CH2
0.0362943 H2O2
0.0844714 H2
0.0862782 CH3
0.105794 CH2O
0.110349 HCO
0.141159 H2O
0.150828 CH3O
0.218864 O
0.294638 HO2
0.48461 OH
0.48475 H
1 O2
1 CH4
1 CO
1 CO2
1 N2

From a detailed 32 species scheme, we obtain reduced schemes (31 to 14 species). and we choose the one with 14 species for the next step because the shape of the velocity and species are conserved (and Cantera is unable to converge the 13-species scheme).

[[File:DRGEPSpec_14Sp_42R_Premixed.png|900px|center]]

Fig1 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 14 transported species and 42 reactions, after a DRGEP species reduction (in red).

From the reduced scheme with 14 species, the DRGEP reaction step displays the associated 42 reactions (forward, reverse and global) with their rank :

Reaction 11 1.76836114590199e-05
Reaction 1 2.00306712724843e-05
Reaction 2 5.32560412611922e-05
Reaction 12 0.000199370652543748
Reaction 22 0.000203838178516555
Reaction 6 0.00205742513026953
Reaction 18 0.00214112144276709
Reaction 31 0.00256497802215946
Reaction 36 0.00423851339874798
Reaction 38 0.00628440315477067
Reaction 10 0.00709110759390656
Reaction 34 0.00727675619860293
Reaction 7 0.00816841794021552
Reaction 32 0.0105674795412113
Reaction 8 0.011392637948932
Reaction 37 0.0121416498847893
Reaction 25 0.0223800727572329
Reaction 24 0.0282453396822729
Reaction 29 0.0283685654460358
Reaction 13 0.0346772420107361
Reaction 9 0.0420990341989184
Reaction 5 0.0436190317079101
Reaction 19 0.052214327287295
Reaction 14 0.0559978780179485
Reaction 40 0.116797747919766
Reaction 3 0.119098963953184
Reaction 35 0.124498803353466
Reaction 26 0.139190739846114
Reaction 21 0.156522233136118
Reaction 30 0.159814723012322
Reaction 20 0.170817390107279
Reaction 39 0.1880142273317
Reaction 23 0.196350171114342
Reaction 4 0.216840758956933
Reaction 15 0.216904850055577
Reaction 42 0.233730982227189
Reaction 17 0.288086975041949
Reaction 27 0.28850598819427
Reaction 16 0.313186383157947
Reaction 33 0.436800577699977
Reaction 41 0.466945029846514
Reaction 28 0.467986201698403

After this step, by comparing the reference trajectories with the new ones, we choose to delete 16 reactions because after 17 reactions removed, the CO2 profile loose its initial shape.
The next step is performed with 14 species and 26 reactions.

[[File:DRGEPR_14sp_26R_Premixed.png|900px|center]]

Fig2 : Comparison between the trajectories of the target species, the temperature and the flame speed computed with the reduced 14-species 42-reaction mechanism (in black) , and the trajectories computed with the reduced mechanism with 14 transported species and 26 reactions after a DRGEP reaction reduction (in red).

=== QSS step ===

The QSS step provides the QSS criteria of each species and the different links with the others species :

Species H 0.0581710482364302
Species O 0.0160759870785582
Species O2 0.277560360139677
Species OH 0.0144373005142915
Species H2O 0.314791474636433
Species HO2 0.010252726793236
Species CH3 0.100336627880574
Species CH4 0.79524736833312
Species CO 0.694064507028327
Species CO2 0.692897407440143
Species HCO 0.00243878401227475
Species CH2O 0.0772557856780877
Species CH3O 0.0207969879289909
Species N2 0

Interactions with species H with QSS Criteria 0.0581710482364302
HO2:2 CH3:1 CH2O:2 CH3O:1 N2:1

Interactions with species O with QSS Criteria 0.0160759870785582
OH:1 HO2:1 CH3:1 CH2O:1 CH3O:1

Interactions with species OH with QSS Criteria 0.0144373005142915
O:1 OH:2 HO2:1 CH3:2 HCO:2 CH2O:1 CH3O:1

Interactions with species HO2 with QSS Criteria 0.010252726793236
H:2 O:1 OH:1 CH3:1 CH2O:1 N2:1

Interactions with species CH3 with QSS Criteria 0.100336627880574
H:1 O:1 OH:2 HO2:1

Interactions with species HCO with QSS Criteria 0.00243878401227475
OH:2

Interactions with species CH2O with QSS Criteria 0.0772557856780877
H:2 O:1 OH:1 HO2:1

Interactions with species CH3O with QSS Criteria 0.0207969879289909
H:1 O:1 OH:1

Interactions with species N2 with QSS Criteria 0
H:1 HO2:1

We choose to put the species CH3O and HCO in QSS hypothesis due to their low QSS coefficient. The species HO2 could have been a good candidate too but it is linked to himself (non linearity).

In order to obtain the trajectories of the 14-species 26-reaction reduced scheme with these 2 species in QSS hypothesis, we run the '''getQSSfile''' step and we obtain the following graphs.We observe that the final state and the shape of the trajectories are conserved. It is under these conditions that the optimisation step will be efficient.

[[File:QSS_12sp_Premixed.png|900px|center]]

Fig3 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after a DRGEp reaction reduction (in red).

=== Optimisation ===

The final step of the ORCh method, the genetic algorithm, enables to recover the trajectories of the target species. Firstly, we allowed a 10 % variation on the pre exponential factor, the temperature exposant and 6 % on the energy activation in order to find their optimal values.

A population of 42 elements was used during 48 generations.

Secondly, in order to obtain more precise trajectories, we allowed a 1 % variation on the pre exponential factor, the temperature exposant and the energy activation. 34 more generations were performed in that case.

The following trajectories of the temperature, the flame speed and the target species match perfectly the ones of the reference detailed scheme with only 12 transported species and 26 reactions.

[[File:Optim_PremixGRI12.png|900px|center]]

Fig4 : Comparison between the reference trajectories of the target species, the temperature and the flame speed (in black), and the trajectories computed with the reduced mechanism with 12 transported species and 26 reactions after optimisation (in red).

== '''Bibliography''' ==

File:DRGEPSpec 14Sp 42R Premixed.png

2019-01-31T15:08:38Z

Seltz: Seltz uploaded a new version of File:DRGEPSpec 14Sp 42R Premixed.png