DEM_Pyrolysis reaction is not happening

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#1

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Hello Developers,
I am beginner to use MFIX solver. I am doing simple biomass pyrolysis 3D
Sim_screenshot
DEM_biomass.mfx (25.1 KB)
usr_rates_des.f (7.0 KB)
simulation using DEM model. I am able to build the usr_des_rates.f file without any errors. Even the simulation is running without any errors and the heat transfer from the gas to the solid is also happening (confirmed with increase in the particle temperature).
But, the reaction is not happening and the reaction rate for pyrolysis is shown always zero and the product gases amounts are also zero. While running simulation, I get something like diffusion coefficient = 0 in the console. I have attached the screen shot of the same below for your kind notice. The input file and des rate files are also attached below for your kind reference. The geometry is taken from biomass DEM tutorial and the rate for pyrolysis reaction is taken from the variable density 2D TFM tutorial problem.
I request you to kindly go through the files and let me know where I am going wrong. I can also give you if you require any other additional inputs. Thanks for the help in advance.

Regards,
Shanmugh D

#2

Upon compiling your code I get:

Building Fortran object CMakeFiles/udfs.dir/tmp/test/usr_rates_des.f.o

/tmp/test/usr_rates_des.f:168:6:

  168 |    ENDIF
      |      1
Error: Expecting END SUBROUTINE statement at (1)
#3

Hai Developer,
Thanks for your response. I have corrected the UDF and it is working fine now. The way I specified the particle temperature in usr_des_rates.f for DEM simulation was not correct. I have changed it now and the reactions are happening now. I will be surely needing your assistance in the near future if I come across with any problems.
Another information required: It will be good to let me know the source for knowing all the keywords used in MFIX.
Thanks again for your response.
Regards,
Shanmugh D

#4

For keyword reference, if you click the “Search” icon search on the top toolbar

shot-2024-03-18_11-31-29
icon

then this popup will appear

shot-2024-03-18_11-33-17
shot-2024-03-18_11-33-17961×623 66.8 KB

you can search within the keywords and their descriptions and find the associated controls in the MFiX GUI

See also this section of the MFiX manual Keyword reference
where the keywords are organized by category rather than straight A-Z

Note that there are a large number of keywords and many of them are for specialized purposes. You do not need to know about all of them. One of the purposes of the MFiX GUI is to make it so that you can use MFiX without knowing every keyword and what it does … and not every keyword has a control in the GUI (for example, the quadric keywords).

If you have any more questions please open a new topic.

Hope this helps.
– Charles

#5

Hello Developer,
Thanks for your quick response. I have got cleared. Thanks for your detailed email.

Regards,
Shanmugh D