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Newtons method failed to converge in 100 iterations

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Old   September 2, 2011, 12:21
Default Newtons method failed to converge in 100 iterations
  #1
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Bostjan
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hey all, after giving all boundary condition for gas combustion, i got following error during solver. Please help me to understand this error.

Anybody are experienced in this? any suggestion on this problem?


Parallel run: Received message from slave
-----------------------------------------
Slave partition : 3
Slave routine : NEWT_FIT
Master location : End of Continuity Loop
Message label : 009100013
Message follows below - :
+--------------------------------------------------------------------+
| ****** Notice ****** |
| Newtons method failed to converge in 100 iterations. This |
| occurred while computing the following variable: |
| |
| Variable Name : Temperature |
| Location Name : Default Domain |
| Mesh location : VERTICES |
| Mesh entity : |
| Last 3 Changes : 1.64457E-01 1.64457E-01 1.64457E-01 |
| 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. |
+--------------------------------------------------------------------+
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Old   September 2, 2011, 18:37
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Glenn Horrocks
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What type of material properties are you using?
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Old   September 3, 2011, 03:10
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Bostjan
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For Gas Air mixture i used reacting mixture, material group: gas phase combustion, mixture properties: ideal mixture

For O2, CO2, H20,...material properties: ideal gas, NASA format

This problem has appeared when i increased heat transfer (heat flux) for 1000- times (from -300 W/m2 to -30 000 W/m2) for wall boundary conditions...

Last edited by brajh11; September 3, 2011 at 03:35.
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Old   September 3, 2011, 05:56
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Glenn Horrocks
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Combustion models are always hard to keep stable. I suspect you will need smaller timesteps to resolve the combustion transient. But that's only a guess.
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Old   September 3, 2011, 06:24
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Bostjan
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i solved my problem steady state not transient.

For Timescale Control i have changed from Auto Timescale to Physical Timescale 0.008s but now the solver said:

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Floating point exception: Overflow |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

Parallel run: Received message from slave
-----------------------------------------
Slave partition : 4
Slave routine : ErrAction
Master location : RCVBUF,MSGTAG=1033
Message label : 001100279
Message follows below - :

+--------------------------------------------------------------------+
| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Stopped in routine FPX: C_FPX_HANDLER |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+
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Old   September 3, 2011, 06:29
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OK, that error message means you have improved things but it still cannot converge. You need smaller time steps.
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