Is the DT curve running like this because of poor mesh quality?
And what should a good DT curve look like?
It is hard to tell. Please try without cell re-indexing turned off to see if it makes a difference.
That DT curve looks fine until it drops to 0. Can you see anything particular happening in the simulation at the time that happens?
There will be a warning code like this appearing:
MFiX running, simulation time: 0.190s elapsed time: 1:42:00
Warning from utilities_mod.f:170
Velocity exceeds limit: 500.0 0
in cell: I = 7 J = 18 K = 13
Epg = 1.0000 Ug = -230.89 Vg = 1924.0 Wg = -269 .69
To change the limit, adjust the scale factor MAX_INLET_VEL_ FAC.
Warning from utilities_mod.f:182
Velocity exceeds limit: 500.00
in cell: I = 11 J = 23 K = 17 M = 1
Eps = 0.10681E-01 Us = -0.89478 Vs = -3067.6 Ws = 0.32284
To change the limit, adjust the scale factor MAX_INLET_VEL_FAC.