Unable to parse transport data
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sagar k
Aug 27, 2015, 11:57:50 AM8/27/15
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Hi
I am trying to convert a CK to cti file. I have Cantera 2.2.0 version. I read through another post wherein the same problem was addressed. In the same way I also tried to comment out some lines. But Still I'm unable to execute the file. The command prompt shows Unable to parse transport data: not enough parameters. Without transport data I don't have any problems in converting to cti file.
Any help would be greatly appreciated. I'm attaching the reaction mechanism files of Butanol downloaded from LLNL https://combustion.llnl.gov/mechanisms/alcohols/butanol-isomers
Regards
Sagar
Ray Speth
Aug 27, 2015, 1:57:14 PM8/27/15
to Cantera Users' Group
Sagar,
The attached files aren't actually the same as the ones on the LLNL web site. In particular, your tran.dat file somehow seems to have been converted to UTF-16. Cantera expects input files to be ASCII or UTF-8.
Regards,
Ray
sagar k
Aug 27, 2015, 4:36:06 PM8/27/15
to Cantera Users' Group
Ray,
Thanks for pointing out. It worked partially. I used the ck2cti file. It showed me the following error. How do I correct this?
Microsoft Windows [Version 10.0.10240]
(c) 2015 Microsoft Corporation. All rights reserved.
C:\Users\Sagark>cd..
C:\Users>cd..
C:\>cd Python34
C:\Python34>python.exe C:\Python34\Scripts\ck2cti.py --input=C:\Python34\Scripts\chem.txt --thermo=C:\Python34\Scripts\therm.txt --transport=C:\Python34\Scripts\tran.txt --permissive
INFO:root:Skipping unexpected species "hoco" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ch3cho2h" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ch3coch2o2h" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ch3coch2o" while reading thermodynamics entry.
WARNING:root:Found additional thermo entry for species c2h5co. If --permissive was given, the first entry is used.
INFO:root:Skipping unexpected species "ch3chcho" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c3h2" while reading thermodynamics entry.
WARNING:root:Found additional thermo entry for species iic4h7q2-t. If --permissive was given, the first entry is used.
INFO:root:Skipping unexpected species "c5h11-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h81-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h91-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h91-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h91-5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h92-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h92-5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h9o1-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h9o2-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2h-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2h-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2h-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h11o2-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh3-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh3-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o1-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o1-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o1-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o1-5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o2-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10o2-4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-2o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-3o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-4o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh1-5o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-1o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-3o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-4o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh2-5o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh3-1o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10ooh3-2o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket12" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket13" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket14" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket15" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket21" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket23" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket24" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket25" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket31" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "nc5ket32" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10oh-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h10oh-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "o2c5h10oh-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "o2c5h10oh-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h6" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*ccjc*c" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "l-c6h4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c-c6h4" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h5oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h5o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "p-c6h4o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "p-c6h3o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "o-c6h4o2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h6" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h5oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h4o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h5o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h4oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h5oo" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h5ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c6h4oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "hoc6h4oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "oc6h4oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "p-oc6h5oj" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "o-oc6h5oj" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c#cc*ccj" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h6-l" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "cj*cc*cc*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*cc*ccj*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "cj*cc*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h3o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c5h7" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "oc5h7o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*ccjc*coh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*cc*ccj" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*cc*cc" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*cc*ccoh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c*ccjc*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "oc4h6o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "oc4h5o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "hoc*cc*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "hoc*ccj*o" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "o2cchooj" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h6oh1-43" while reading thermodynamics entry.
WARNING:root:Found additional thermo entry for species c2h3oh. If --permissive was given, the first entry is used.
INFO:root:Skipping unexpected species "c4h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic3h7oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic3h6oh-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c3h5oh1-1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c2h5oc2h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ch3oc2h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ch2oc2h5" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "hcchoh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h8oh-1oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h8oh-2oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h8oh-3oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h8oh-4oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-1ooh-2ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-1ooh-3ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-2ooh-3ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-2ooh-4ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-3ooh-4ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "c4h7oh-1ooh-4ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h7oh-12ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h7oh-13ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h7oh-23ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h7oh-33ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h8oh-1oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h8oh-2oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "ic4h8oh-3oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "tc4h7oh-ooh-ooh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "tc4h8oh-oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h223" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h212" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h213" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h2m1" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h2m2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4o5h2m3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4ohket1-2" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4ohket1-3" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4ohket1-m" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4h8oh-moh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4h8oh-1oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4h8oh-3oh" while reading thermodynamics entry.
INFO:root:Skipping unexpected species "sc4h8oh-2oh" while reading thermodynamics entry.
WARNING:root:Ignoring duplicate transport data for species "c4h8o1-4 on line 107 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "ch3co on line 291 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "c4h8-2 on line 1207 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "c4h8-1 on line 1209 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "c2h5cho on line 1223 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "ch3choococh3 on line 1365 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "pc4h9o on line 1584 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "tic4h7q2-i on line 1848 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "iic4h7q2-t on line 1849 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "iic4h7q2-i on line 1850 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "ch2cch2oh on line 1865 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "c2h3o1-2 on line 1873 of "C:\Python34\Scripts\tran.txt".
WARNING:root:Ignoring duplicate transport data for species "c2h3oh on line 1902 of "C:\Python34\Scripts\tran.txt".
Wrote CTI mechanism file to 'C:\\Python34\\Scripts\\chem.cti'.
Mechanism contains 431 species and 2551 reactions.
Validating mechanism...
**** WARNING ****
For species ch3o2, discontinuity in cp/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 11.5313.
Value computed using high-temperature polynomial: 11.5482.
**** WARNING ****
For species c2h2oh, discontinuity in cp/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 12.2546.
Value computed using high-temperature polynomial: 12.2718.
**** WARNING ****
For species ch2co, discontinuity in cp/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 10.0876.
Value computed using high-temperature polynomial: 10.1013.
**** WARNING ****
For species c4h612, discontinuity in cp/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 20.128.
Value computed using high-temperature polynomial: 20.1809.
**** WARNING ****
For species ch3chchco, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 54.1203.
Value computed using high-temperature polynomial: 56.1447.
**** WARNING ****
For species ch2chchcho, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 54.1203.
Value computed using high-temperature polynomial: 56.1447.
**** WARNING ****
For species c2h3choch2, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 55.5755.
Value computed using high-temperature polynomial: 53.053.
**** WARNING ****
For species c4h5-2, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 52.4292.
Value computed using high-temperature polynomial: 54.3208.
**** WARNING ****
For species c4h6-2, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 50.2514.
Value computed using high-temperature polynomial: 51.5152.
**** WARNING ****
For species ch3chchcho, discontinuity in cp/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 22.4214.
Value computed using high-temperature polynomial: 22.3333.
**** WARNING ****
For species ch3chchcho, discontinuity in s/R detected at Tmid = 1000
Value computed using low-temperature polynomial: 59.1945.
Value computed using high-temperature polynomial: 62.4953.
FAILED.
***********************************************************************
CanteraError thrown by checkReactionBalance:
The following reaction is unbalanced: oh* <=> h + oh
Element Reactants Products
H 1 2
***********************************************************************
I tried to balance the reaction by adding 2 to the hydroxy radical. But then it gave me an error as 0 elements. Could you please tell me where am I going wrong.
Thanks and Regards
Sagar
sagar k
Aug 28, 2015, 5:44:02 AM8/28/15
to Cantera Users' Group
Ray,
I found the problem. I had apparently made some changes in the input file. In the original chem.txt file, for the oh* the mechanism is oh* <=> oh + hv (light). But When I try to convert it, it is showing that 'hv' is unexpected species. How do I resolve this problem?
Regards
Sagar
Nick Curtis
Aug 28, 2015, 10:22:20 AM8/28/15
to Cantera Users' Group
Sagar,
Cantera doesn't currently support H chemiluminescence reactions
You can comment it out (they generally have minimal effects on the mechanism)
Nick
Cantera doesn't currently support H chemiluminescence reactions
You can comment it out (they generally have minimal effects on the mechanism)
Nick
Thomas Fiala
Aug 28, 2015, 1:49:21 PM8/28/15
to Cantera Users' Group
Sagar,
Generally, you could ignore the entire reaction. Compared to chemical and thermal formation and destruction rates of OH*, the rates from spontaneous transition and absorption are much lower. (unless you have laser excitation)
Thomas
Ray Speth
Aug 28, 2015, 4:23:00 PM8/28/15
to Cantera Users' Group
Hi all,
The Arrhenius expression clearly doesn't provide enough information to compute the reverse rate, since you would also need to know both the incident photon flux as well as the absorption cross section. It could be treated as an irreversible reaction, which would represent the chemiluminescent reaction, but even in that case, there would be a (probably small) problem with writing the energy conservation equation, since the emitted photon is presumably not immediately absorbed, and therefore should be accounted for in a loss term.
Regards,
Regards,
Ray
Bryan W. Weber
Aug 29, 2015, 9:17:14 AM8/29/15
to Cantera Users' Group
Hi Ray,
I think it would be OK if Cantera ignores them and prints a message to the screen, perhaps only if --permissive is given. If you look at the Butanol mechanism on line 388: https://combustion.llnl.gov/content/assets/docs/combustion/butanol_isomers_CnF_ver7_mech_inp.txt
You can see that Bill Pitz makes a note that CHEMKIN 3 does essentially the same thing (and I assume future versions of Chemkin do as well). I looked at the old mechanism interpreter, and it looks like that expects a supplemental line with the format HV/info/ to provide the extra parameters for radiation enhanced reactions. This file (https://www.princeton.edu/~lam/documents/LSTEP/CHEMKIN/CHEMKIN0.folder/interp.f) has this to say:
C If the reaction contains a radiation wavelength, this is C indicated by the presence of an 'HV' either as a reactant C or as a product. Unless otherwise defined on additional C lines as described in (2), the value of the wavelength is C -1.0 if a reactant or +1.0 if a product.
However, I can't really find anything in the docs that indicates how that radiation is handled.
Best,
Bryan
sagar k
Sep 1, 2015, 4:14:40 AM9/1/15
to Cantera Users' Group
Hi
I removed the reaction and there was no problem with conversion. Thank you for your inputs.
I have one more question regarding handling of input file. In the input file there are no units written, but when the files is converted to cti, a units directive is put on the top of the file giving default units specified in the file. How does cantera or for that matter, ck2cti.py recognize units in the input files?
Regards
Thomas Fiala
Sep 1, 2015, 4:29:30 AM9/1/15
to Cantera Users' Group
I agree with Bryan that ignoring the reaction and printing a warning would be the best thing to do. At least, as long as these reactions feature excited states like OH* or CH*, and not models for computing IR radiative loss by H2O or CO2 (I don't know if that's anywhere the case, though).
Like Ray pointed out, computing the formation of the excited molecule by absorption would require the implementation of additional features that are not trivial to implement.
To account for the reverse process, the spontaneous transition from the excited to the ground state, the reaction could be implemented as a one-way reaction. There would be no problem in terms of energy, as excited and ground state should have a difference in energy of formation corresponding to the radiative loss. Nevertheless, the amount of energy radiated e.g. by OH* or CH* is so small that it can be safely ignored.
I used such a one-way reaction for OH* in non-premixed counterflow flames. However, I found out that I could have completely ignored this reaction in the mechanism because its rates are by orders of magnitude smaller compared to the thermal and chemical formation and destruction (quenching) of OH*. I think that this should be valid for most other luminescent species as well.
For the case that someone is interested in the emissivity of such an excited radical: Typically, the reaction rate for the spontaneous transition consists of only the pre-exponential Arrhenius factor. This corresponds to a lumped Einstein coefficient for all molecular transitions modeled. Therefore, the reaction rate, which represents the emissivity, is directly proportional to the concentration of the excited molecule. The transition reaction itself does not have to be included to compute the emissivity.
Therefore, ignoring such reactions or treating them as one-way reactions should both work fine and shouldn't make a difference.
Best regards,
Thomas
Like Ray pointed out, computing the formation of the excited molecule by absorption would require the implementation of additional features that are not trivial to implement.
To account for the reverse process, the spontaneous transition from the excited to the ground state, the reaction could be implemented as a one-way reaction. There would be no problem in terms of energy, as excited and ground state should have a difference in energy of formation corresponding to the radiative loss. Nevertheless, the amount of energy radiated e.g. by OH* or CH* is so small that it can be safely ignored.
I used such a one-way reaction for OH* in non-premixed counterflow flames. However, I found out that I could have completely ignored this reaction in the mechanism because its rates are by orders of magnitude smaller compared to the thermal and chemical formation and destruction (quenching) of OH*. I think that this should be valid for most other luminescent species as well.
For the case that someone is interested in the emissivity of such an excited radical: Typically, the reaction rate for the spontaneous transition consists of only the pre-exponential Arrhenius factor. This corresponds to a lumped Einstein coefficient for all molecular transitions modeled. Therefore, the reaction rate, which represents the emissivity, is directly proportional to the concentration of the excited molecule. The transition reaction itself does not have to be included to compute the emissivity.
Therefore, ignoring such reactions or treating them as one-way reactions should both work fine and shouldn't make a difference.
Best regards,
Thomas
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