No reaction shows when using DEM with reaction

MFiX
#1

fb_2019-09-25T171522.130432.zip (245.2 KB)
Hello, everyone.

I am a beginner. I want to add one simple reaction following the user guide: methane combustion
‘CH4+2O2–>CO2+2H2O’

I used the DEM model and only added 5 sand particles which will not take part in the reaction.

Then, I modified the “usr_rates.f” and “usr_rates_des.f”（the latter is empty). And I rebuild the solver through GUI rebuild button.

Everything is fine EXCEPT nothing happened about the reaction–I can’t observe any CO2 or H2O generated, nor the RRrates_1. (the value is always zero no matter how scaled up)

#2

It looks like you have an error in your rates file.

RATES(R1) = 6.7d12 * exp(-2.4358d4/T_g(IJK)) * &
            EP_g(IJK) * c_O2**1.3 * CH4**0.2

I’m guessing that the CH4 should be c_CH4

#3

Thank you. But it seems that is not the reason, since even after I corrected the typo, it still did’t working

#4

You should not have renamed the subroutine as USER_RATES. The correct name is USR_RATES

The reaction rate is likely too large (it runs but fails with DT_MIN error).

2 Likes
#5

It works!
Thank you! It is really helpful!

1 Like
Still no chemical reaction occurring
#6

hi chunlei
I downloaded your zip file and alter your USER_RATES by the following reply.
It run well but I can’t observe any CO2 or H2O generated.
can I get your QQ
Thanks

#7

leave your email, I will contact you and send you a new file

#8

1017500384@qq.com
thanks