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-   -   Newtons method failed to converge in 100 iterations (http://www.cfd-online.com/Forums/cfx/92113-newtons-method-failed-converge-100-iterations.html)

brajh11 September 2, 2011 12:21

Newtons method failed to converge in 100 iterations
 
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. |
+--------------------------------------------------------------------+

ghorrocks September 2, 2011 18:37

What type of material properties are you using?

brajh11 September 3, 2011 03:10

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...

ghorrocks September 3, 2011 05:56

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.

brajh11 September 3, 2011 06:24

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 |
| |
| |
| |
| |
| |
+--------------------------------------------------------------------+

ghorrocks September 3, 2011 06:29

OK, that error message means you have improved things but it still cannot converge. You need smaller time steps.


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