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Old   October 31, 2008, 04:17
Default Newton's method failed to converge
  #1
Mohan
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dear all, I am solving multicomponent system using Eulerian approach in CFX-11.0 The CFX solver works fine and converges when the flow and scalar are solved. But when I turn on the energy balance i get the following error and run stops with "overflow" message. Kindly share your experience dealing with following message.. +--------------------------------------------------------------------+ | ****** Notice ****** | | Newtons method failed to converge in 100 iterations. This | | occurred while computing the following variable: | | | | Variable Name : LIQUID.Temperature | | Location Name : StationaryNozzle | | Mesh location : VERTICES | | Mesh entity : | | Last 3 Changes : 5.44100E+00 1.02020E+01 4.46600E+00 | | Tolerance : 1.0000E-02 | | | | The Newton iteration was either slowly converging or has stalled. | | The solver will continue with the variable set as it was on the | | final iteration. If this situation continues you might try | | increasing the number of iterations allowed for Newtons method. | | This can be changed by setting one of the parameters: | | | | Temperature : "Constitutive Relation Iteration Limit" | | Pressure : "Newton Pressure Iteration Limit" | | | | for your mixture using the definition file editor. | +--------------------------------------------------------------------+

-regards, mohan
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Old   October 31, 2008, 17:09
Default Re: Newton's method failed to converge
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John S.
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In my experience I see this error 9 out of 10 times when I have bad grid. If I can't get around it with expert parameters I usually just repent, remesh, rerun.
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Old   November 1, 2008, 00:33
Default Re: Newton's method failed to converge
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Mohan
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Thanks John, Kindly mention the expert parameters that you had to adjust. --regards, mohan
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Old   November 24, 2008, 03:53
Default Re: Newton's method failed to converge
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JDP
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Mohan, you can add the expert parameter pertaining to "Newton Pressure Under relaxation" in the Library tab. You can select the Material you are using as the working fluid and add the expert parameter mentioned above. The default value is 1. You can reduce this value in order to avoid the problem. Hope this will work.
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