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#1 |
Member
K
Join Date: Jul 2017
Posts: 97
Rep Power: 9 ![]() |
Dear foamers,
I want to define a new type of reaction rate coefficients in OpenFoam for my case. The source of inspiration could be the ThirdBodyArrhenius reaction rate of OpenFOAM (in src/thermophysicalModels/specie/reaction/reactionRate/thirdBodyArrheniusReactionRate/). Could you explain me how the reaction should look like when it comes to define the third bodies species ? Like if I look at tutorial case of openFOAM for reactingFOAM solver in tutorials/combustion/reactingFoam/laminar/counterFlowFlame2D/: in constant/reaction, we have : Code:
species ( O2 H2O CH4 CO2 N2 ); reactions { methaneReaction { type irreversibleArrheniusReaction; reaction "CH4 + 2O2 = CO2 + 2H2O"; A 5.2e16; beta 0; Ta 14906; } } so, lets say that I want to modify this reaction in the following way : Code:
1 species 2 ( 3 O2 4 H2O 5 CH4 6 CO2 7 N2 8 ); 9 10 reactions 11 { 12 methaneReaction 13 { 14 type irreversiblethirdBodyArrheniusReaction; 15 reaction "CH4 + 2O2 + M = CO2 + 2H2O + M"; 16 A 5.2e16; 17 beta 0; 18 Ta 14906; 19 tbes 1.0; 20 defaultEfficiency 1.0; 21 M CO2/N2; 22 } 23 } First, if I remove the line 20, I would have an error saying there is no mention of defaultEfficiency. However, I don't see anywhere in src/thermophysicalModels/specie/reaction/reactionRate/ this parameter being defined. What is the difference between tbes (which stands for thirdBodyEfficiencies) and defaultEfficiency ? Second, in thirdBodyArrheniusReactionRate there is no input named as M. The inputs are : Code:
const scalar A, const scalar beta, const scalar Ta, const thirdBodyEfficiencies& tbes Thanks in advance for your help, Best regards, Mary P.S.: I am using the version 4.x of OpenFOAM. |
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#2 |
Super Moderator
Niklas Nordin
Join Date: Mar 2009
Location: Stockholm, Sweden
Posts: 693
Rep Power: 29 ![]() ![]() |
go to
tutorials/combustion/chemFoam/h2 run chemkinToFoam chemkin/chem.inp chemkin/therm.dat chemkin/transportProperties chem.inp therm.inp to convert chemkin format files to foam format. check the chem.inp file and compare it with chemkin/chem.inp so for instance this reaction in chemkin. H+O2(+M)=HO2(+M) 4.52E+13 0.0 0.0 !MARINOV 1995A LOW / 1.05E+19 -1.257 0.0 / !MARINOV 1995A H2O/0.0/ H2/0.0/ N2/0.0/ converts to un-named-reaction-3 { type reversibleArrheniusLindemannFallOffReaction; reaction "H + O2 = HO2"; k0 { A 1.05e+13; beta -1.257; Ta 0; } kInf { A 4.52e+10; beta 0; Ta 0; } F { } thirdBodyEfficiencies { coeffs 10 ( (H2 0) (H 1) (O2 1) (O 1) (OH 1) (HO2 1) (H2O2 1) (H2O 0) (AR 1) (N2 0) ) ; } } |
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#3 |
Member
K
Join Date: Jul 2017
Posts: 97
Rep Power: 9 ![]() |
Thanks Niklas. Your reply answers totally to my question and gives me enough insight to create the new type of reaction rate coefficients.
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Tags |
new reaction model, openfaom, reactingfoam, thirdbody reaction rate |
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