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Error: Divergence detected in AMG solver

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Old   October 18, 2010, 17:16
Post DPM Error: Divergence detected in AMG solver
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Hello friends,

I am encountering either of two errors (given below) when running DPM in Fluent for a turbulent, incompressible, rotating internal flow (like flow inside an annular cylinder).

# Divergence detected in AMG solver: w-swirl -> Increasing relaxation sweeps!
# Divergence detected in AMG solver: k -> Increasing relaxation sweeps!

I am using 2D axisymmetric with swirl option here. Before DPM simulation, I first solved for the flow itself using pressure based solver and obtained a converged solution.

The errors came up immediately after solver restarts from that converged solution. I don't get what they meant. Is it that the k & swirl residuals are too small now as flow has converged and by activating dpm, they will increase backwards. Is that not permitted to do?

Can anyone please explain me what the solver is trying to imply here?

Last edited by siri; October 19, 2010 at 10:00. Reason: to improve question
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Old   October 20, 2010, 12:01
Default any ideas, huh !
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Quote:
Originally Posted by siri View Post
Hello friends,

I am encountering either of two errors (given below) when running DPM in Fluent for a turbulent, incompressible, rotating internal flow (like flow inside an annular cylinder).

# Divergence detected in AMG solver: w-swirl -> Increasing relaxation sweeps!
# Divergence detected in AMG solver: k -> Increasing relaxation sweeps!

I am using 2D axisymmetric with swirl option here. Before DPM simulation, I first solved for the flow itself using pressure based solver and obtained a converged solution.

The errors came up immediately after solver restarts from that converged solution. I don't get what they meant. Is it that the k & swirl residuals are too small now as flow has converged and by activating dpm, they will increase backwards. Is that not permitted to do?

Can anyone please explain me what the solver is trying to imply here?
Can anyone respond to this please. guys.... where are you
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Old   October 21, 2010, 05:50
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Laurence Wallian
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perhaps you can try to reduce some under-relaxation factors...
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Old   October 21, 2010, 14:34
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thanks laurence, for stopping by. i did try that ... it doesn't seem to matter but.
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