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Error: Divergence detected in AMG solver

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Old   November 15, 2015, 04:01
Default Error: Divergence detected in AMG solver
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Masroor
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Hi,
I need to discuss a matter that I faced while simulating a multiphase system using different multiphase and turbulence models. In all the cases I kept the operating conditions and under relaxation factors similar. I got corrected results without any error using eulerian model with k-epsilon standard, k-omega standard models while the case including same multiphase model but RS turbulence model yielded an error "Error: Divergence detected in AMG solver: epsilon" with a notification in text user interface which is "turbulent viscosity limited to viscosity ratio of 1.0 e+05 in xxxxx cells".
Kindly provide any any solution for above mentioned
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Old   November 16, 2015, 11:50
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Lucky Tran
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Two things are going on here. The first is that your solution diverged, it's as simple as that. The RSM model is notoriously difficult to get a converged solution because it is very sensitive. You should investigate whether it converged because of a bad initial guess or if there is another numerical issue that is causing the issue (skewed cells in mesh for example). You may be able to proceed using reduced urf's.

Turbulent viscosity being limited means that your turbulence model is predicting highly non-physical results, and this can be a result of a bad initial guess. For example, if you didn't properly initialize all the Reynolds stresses & k & epsilon you could easily end up with this error.
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