Divergence detected in AMG solver
 

Hi everyone!

I am new to simulations of multiphase flow, and I am trying to simulate a fluidized bed using a DEM approach. I am using Fluent to simulate the fluid part. Unfortunately I am encountering an error when I launch the coupled simulation. After a few time-step this error is displayed:

# 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

Do you have any suggestion about how to solve this issue?
Any reply will be appreciated!
Thank you

Hi there,

As this isn't occurring on the first time step/iteration, it is likely that your simulation is simply diverging. I would suggest lowering your Courant number and relaxation factors for pressure, momentum and volume fraction. You may need to reduce them significantly until the simulation has advanced far enough to become stable.

Regards,
Sean

Sean, thank you for your reply! I have tried to lower significantly the URF but unfortunately this didn't help...