No reaction observed when trying methane combustion

MFiX How to
#1

Hello everyone!

I am following the chemistry 4.13.3.5 tutorial: methane combustion, and I can get it to run without any errors, but when I look at my results, the amount of the reactants and products is the same at the beginning and the end, appearing as though no reaction took place.

I created the usr_rates.f file, copied how it was shown in the tutorial, rebuilt the solver, and am not getting any errors while running it, so I am not sure where I am messing up. I don’t know if I am missing something in the GUI or if I am missing a needed file, but the reaction does not seem to happen, so I would love some help! I attached my mfix and usr_rates.f files below.

I also am not 100% sure the purpose of the usr_rates.f file, and how this tutorial is different from the 4.13.3.1 tutorial that is also methane combustion but without UDF and usr_rates.f. I would really appreciate the help!

Thanks,
Amanda

temp.mfx (12.5 KB)
usr_rates.f.txt (784 Bytes)

#2

@amanda.baumann - the file should be named usr_rates.f and not usr_rates.f.txt - did you just use that name to upload the file?

Line 1 of the file you poste### usr_rates.f:d triggers a compiler error:

 ==============================================================
                      BUILD FAILED
==============================================================
/tmp/amanda/usr_rates.f:1:0:

    1 | ### usr_rates.f:
       |  
Error: invalid preprocessing directive ###

Your file:

### usr_rates.f:
SUBROUTINE USR_RATES(IJK, RATES)

Note that the # sign is not a comment character in Fortran.

Fixing this and trying again, we get

Error: Symbol ‘o2’ at (1) has no IMPLICIT type

which means that you need to add:

INCLUDE 'species.inc'

I see that this is missing from the example in the documentation, will fix for next release.

Also note that one of our planned developments is to make the specification of reaction rates simpler, this usr_rates.f has proven to be a bit of a pitfall for users.

– Charles

#3

Please refer to the latest documentation if you are using 21.1 version: 4.13.3.5. Example: Methane Combustion with UDF — MFiX 21.1 documentation
(the older documentation was updated for 21.1 version)