Disparity in Fluidization Results: Gidaspow vs. BVK2

MFIX-Exa
4

@oyedejifemi I think this is probably a better starting point for this problem:
inputs.txt (9.1 KB)

Notes:

  • it has at least 4 cells in the depth. That’s probably an absolute minimum. You really shouldn’t be using “standard” CFD-DEM for a bed this thin. We’ve considered it previously, but I dropped it b/c it’s just too thin.
  • IC generates 28,127 particles, the expected number for this case is 24750. I would play around w/ your IC a little more to get this closer
  • When I first ran it, I noticed particles were getting slammed into the po with Gidaspow drag. like what happened in this case. You can ease the initial transient by making the inflow velocity ramp up from zero in time:
bc.inflow.fluid.velocity =  0.0  0.0  1.0    0.0
bc.inflow.fluid.velocity =  2.0  0.0  1.875  0.0
  • I have a couple cases running rn, I’ll confirm tomorrow and report back but it looks like the BVK2 case is just barely fluidized. This isn’t surprising… you could probably say this is expected. I’ve always found Umf (Gidaspow) < Umf (DNS drag laws) and since you’re setting a single inlet velocity (that is supposed to be approx. 1.5x Umf found in the exp), it’s entirely possible that this is actually (just using random numbers for example) 1.6x Umf for the Gidaspow simulation and 1.2x Umf for the BVK2 simulation.