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Old   December 25, 2008, 05:59
Default AMG Divergence problem
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i am solving mixed convection over circular cylinder when the flow is from top to bottom( buoyancy opposing flow)..after giving all the conditions in fluent i am getting error like "

Error: divergence detected in AMG solver: temperature Error Object: ()

"... why do we get that problem..? i am giving inlet and stream temperatures 300 k and on surface of the cylinder it is 310 k. i am using boussinesq approximation for density. why we will get that problem..? is it due to grid..? i am using circular domain...

please help me in this regard if anybody knows about this problem. thank you in anticipation...

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Old   December 30, 2008, 02:51
Default Re: AMG Divergence problem
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The error just means that the solution is diverging. Try the following:

Change the under-relaxation factor for Pressure to 0.7 and for Momentum to 0.3.

If still not OK, then use ideal gas for the density.

If still not OK, reduce the URF for all parameters to a low value. Increase the value when the residuals have stabilised. Please ensure the URF value for energy at the end of your simulation is high (ideally 1).

Let me know how it goes.

Hope that helps.
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