The software does not report an error, but automatically stops running

Dear developer,
I want to simulate the moving bed shown as figure. However, the mfix model automatically stops running in 0.5 s. Could you help me find out the reason?
In addition, I would like to ask two questions: 1. Whether the escape number or velocity of particles in outlet BC can be controlled? 2. In outlet_particles, how to let particles pass but not gas?
Thanks a lot!

moving_2D.mfx (31.4 KB)
usr_rates_des.f (8.0 KB)

The mfix version is 21.4.

Hi -

In general when seeking help it’s best to provide the .LOG files as well as the inputs - if you go to the main MFiX menu and select “Submit bug report” this creates a ZIP file you can upload that contains useful diagnostic information.

Second - you are running an old version of MFiX, it’s good to update if possible. Note that MFiX 22.4 will be released this week so you may want to wait for that to upgrade.

Having said that - running on the latest MFiX I am able to reproduce this error, but I get better diagnostic info:

#0 desgrid_MOD_desgrid_neigh_build
        at des/desgrid_mod.f:1060
#1 neighbour_mod_MOD_neighbour
        at des/neighbour.f:65
#2 des_time_march_MOD_des_time_step
        at des/des_time_march.f:234
#3 run_dem
        at mfix.f:211
#4 run_mfix
        at mfix.f:146
#5 main_MOD_run_mfix0
        at main.f:79

Here’s the code where the error is happening:

1054	         do lk = lkc-kl_off,lkc+ku_off
1055	         do lj = ljc-jl_off,ljc+ju_off
1056	         do li = lic-il_off,lic+iu_off
1057	            lijk = dg_funijk(li,lj,lk)
1058	            ltotpic =dg_pic(lijk)%isize
1059	            do lpicloc = 1,ltotpic
1060	               lneigh = dg_pic(lijk)%p(lpicloc)

Using the debugger:

(gdb) p lijk
$3 = -1968
(gdb) p li
$4 = 3
(gdb) p lj
$5 = 82
(gdb) p lk
$6 = 0

The code is attempting to access the array dg_pic outside of it’s valid bounds. This kind of problem is often, but not always, due to particles leaving the domain, often due to poor mesh quality or insufficient spring stiffness.
See for example

If that does not help please follow up here, thanks.

– Charles

OK, thank you for your patient answer.

Hello, I would also like to set the particle outlet and inlet for a specified number of particles, is this possible?

Please start a new thread, and attach your files if you want help. Thanks.