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Old   January 15, 2012, 08:44
Default cyclone analysis error
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arjun
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hi all,

i am working with analysis of cyclone dust collector.
i have followed the cyclone tutorial available with me.
but while running the simulation in FLUENT i found following error.


reversed flow in 140 faces on pressure-outlet 13.
# 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 Object: #f

please help me.
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Old   January 15, 2012, 09:32
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Hi,
this means that the solution diverges:
- what model are you using? (you can use k-epsilon RNG with swirl dominated flow enabled, solve for flow and then turn on dpm injection(s))
- what resolution methods?
- are you sure you have a good quality mesh?
- what boundary conditions? (you can use outflow as outlet boundary and velocity inlet as inlet)
- the solver diverges when you start simulation or after how many iterations?
- steady or unsteady simulation?If unsteady what is the time step?

Daniele
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Old   January 15, 2012, 09:56
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i get this error after 11 iteration.
solution is not diverged.

i am using steady state analysis.
minimum mesh quality is 0.5.
second order scheme.
with velocity inlet and outflow boundry conditions.

it gives error. solution is not diverged at all.
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Old   January 17, 2012, 09:09
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shoeb khan
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Quote:
Originally Posted by arjun3020 View Post
i get this error after 11 iteration.
solution is not diverged.

i am using steady state analysis.
minimum mesh quality is 0.5.
second order scheme.
with velocity inlet and outflow boundry conditions.

it gives error. solution is not diverged at all.
Divergence is the most difficult problem to solve in fluent ...
You can try as following
steady analysis is ok!!
mesh size doesn't matter much for divergenve.
use first order scheme.
use velocity inlet and pressure outlet bc.
try to solve flow first and then inject the particles into the domain
use a lower value for momemtum and pressure for underrelaxation factor

try to change your mesh type.

regards
shk
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Old   May 15, 2014, 01:05
Default Multiphase phase (gas-solid) flow using DDPM MODEL medel ( divergence problem
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Hi every one....
i am trying to simulate a solid-gas fluidized bed USING DDPM +DEM MODEL
I GOT FOLLOWING ERROR

# 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 Object: #f

THANKU IN ADVANCE
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