[Iman Afrooz]

Hello everyone,

I am new in Fluent and I am trying to simulate a 3D Fluidized Bed having cylindrical geometry.The geometry is a cylinder Bed with diameter of 7.62 cm and the height of 500 cm, an Airbox with the same diameter but with length of the 17 cm And a distributor plate having 21 holes in between. The diameter of holes are 1 mm with the length of 5 mm (Photo is attached). The velocity inlet is applied at the bottom surface of the Airbox. The pressure outlet is applied at the top surface of the Bed. The sand particles are injected to the system using file injection. I used DPM technique but I faced with the following errors after 3 iterations:

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Updating solution at time level N... done.
Injecting 41595 particle parcels with mass 0.540735 at t = 0

Advancing DPM injections ....
number tracked = 41595, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0
number tracked = 41595, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0
number tracked = 41595, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0
number tracked = 41595, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0
number tracked = 41595, escaped = 0, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0
iter continuity u-air v-air w-air time/iter
1 1.0000e+00 3.9691e-02 9.0649e-01 5.7379e-01 0:00:49 49
2 1.0000e+00 3.2715e-01 4.2793e-01 2.9460e-01 0:00:38 48
3 1.0000e+00 1.8774e-01 3.0985e-01 1.4735e-01 0:00:30 47
# Divergence detected in AMG solver: mp-x-momentum -> Decreasing coarsening group size!
# Divergence detected in AMG solver: mp-x-momentum -> Increasing relaxation sweeps!
# Divergence detected in AMG solver: pressure correction -> Turning off correction scaling!
# Divergence detected in AMG solver: pressure correction -> Increasing relaxation sweeps!

Error: Divergence detected in AMG solver: pressure correction

Error: Divergence detected in AMG solver: pressure correction
Error Object: #f
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I think the problem is due to the coarse meshing that is expanded from small holes of distributor plate to the big cylinder of the bed. So if I can write UDF codes then this problem might be solved. But I don't know how to write CFD codes. Can someone please give me help on this problem by writing UDF for me?

Thank you in advance.