Why didn't the pyrolysis reaction proceed?

When I ran the following case, I found that the mass fraction of the gases didn’t change except for the O2 and CO2 that were passed in.
I used a monitor to check if the reaction was going on, but Pyrolysis and R1 cannot be selected and it didn’t show the rate of the reaction in the results (as shown in the graph).
I don’t know why I have the above two problems, can you please help me out?Thank you!

biomass pyrolysis-0301.mfx (27.3 KB)
usr_rates.f (4.5 KB)
usr_rates_des.f (3.4 KB)

Hi, what version of MFiX are you running? I loaded this case in 23.4.1 and found that I could select Pyrolosis and R1 in the “probe reaction rates” monitor. What happens when you try to select these?

Note that I find it often better to use a “max” type monitor across the entire domain rather than a value in a single cell.

You have declared the reaction rate as INTEGER so the rate values get rounded down to 0. Please replace line 31 or user_rates_des.f by


Your probe monitor is a point region. It is better to use a volume and take the min, max or average over that volume if you want a representative monitor. You only have 100 biomass particles so it is unlikely you will get them to pass exactly through the probe location.

Also keep in mind that reaction rates can be monitored either as “cell data” or “particle data”

Hi, I loaded this case in 23.3.2 and I’m trying to use “cell data” to monitor reaction rates, there is still the problem I described before: I can check pyrolysis and R1, but once I save the project, both reactions uncheck again.

I have the problem in the picture after I changed the code, why is this?

biomass pyrolysis-0301.mfx (27.6 KB)
usr_rates.f (4.5 KB)
usr_rates_des.f (3.4 KB)

The problem with selecting monitors was fixed in the latest version 23.4.1

Running with the latest version (23.4.1) I get this more detailed error rather than the one you saw:

Error: There exists a NORMAL particle in a GHOST cell.
Particle may have gone OUT-OF-BOUNDS.
To resolve this issue, please consider:
 a) Verify all wall boundary conditions are defined
 b) Reducing the value of the variable NEIGHBOR_SEARCH_N (Solids>DEM>Max steps between neighbor search)
 c) Increasing the particle and/or wall stiffness (Solids>DEM>Normal spring constant or Young's modulus)
Current particle location (x, y, z coordinates):-0.3003E-01, -0.1906    , -0.2681E-02
Current particle velocity (u, v, w components) : -44.76    ,   223.0    ,  -6.687

You also have 8 warnings, some of which look serious. Try to resolve the issues in the warnings.


Hi,I’ve addressed some of the issues in the warnings, there’s one last problem I can’t solve.

But when I solved these warnings I still have the above problem, can you help me again?
biomass pyrolysis-0301.mfx (28.1 KB)
usr_rates.f (4.5 KB)
usr_rates_des.f (3.4 KB)