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July 14, 2012, 12:00 
"Newtons method failed in Atomization Problem

#1 
Member
Ahmet
Join Date: Mar 2011
Location: Ankara/ Turkey
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I m simulating spray of heptane. Liquid heptane sprays from an injector. but after injection began, I got this error. Because of specific heat depends on temperature, I m using Nasa polynomials. If I take a specific value for specific heat, the error doesn' t happen. How can I solve this problem?
****** Notice ******   Newtons method failed to converge in 100 iterations. This   occurred while computing the following variable:     Variable Name : Temperature   Location Name : Flow Domain 1   Mesh location : VERTICES   Mesh entity :   Last 3 Changes : 6.25499E02 4.23251E02 4.36934E02   Tolerance : 1.0000E02     The Newton iteration was diverging. The solver will continue   with the variable field as it was on the final iteration. If   this situation continues you might try decreasing the Newton   iteration under relaxation factor. This can be changed by   setting one of the following parameters:     Temperature : "Constitutive Relation Under Relaxation"   Pressure : "Newton Pressure Under Relaxation"     for your mixture using the definition file editor.  ++ Last edited by a_cucen; July 14, 2012 at 13:38. 

July 15, 2012, 05:14 

#2 
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Ahmet
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I solved the problem. But now I have another problem :S It gave this failure after 10 iterations from spray began. How can I solve this problem?
Parallel run: Received message from slave  Slave partition : 4 Slave routine : get_TWFTFC Master location : End of Continuity Loop Message label : 009100015 Message follows below  : ++  ****** Notice ******   The nondimensional near wall temperature (T+) has been clipped   for calculation of Wall Heat Transfer Coefficient.     Boundary Condition : piston   T+ clip value = 1.0000E10     If this situation persists and you are using the High Speed Model,   consider enabling Mach number based blending between low speed and   high speed wall functions. You can do so by specifying a Mach   number threshold as follows:     EXPERT PARAMETERS:   highspeed wf mach threshold = 0.1 # default=0.0 (off)   END  ++ 

July 15, 2012, 08:28 

#3 
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Glenn Horrocks
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If you are modelling multiphase spraying with NASA polynomial fluids then you should expect a numerically unstable simulation. You need to get each bit of this model working one at a time before doing the entire simulation.


July 15, 2012, 20:04 

#4 
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Ahmet
Join Date: Mar 2011
Location: Ankara/ Turkey
Posts: 37
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I have fixed this error too. But there is something I can not explain. The liquid heptane particles are vapourised meanwhile it enters the domain. It must enter the domain in liquid form and break up to small particles in normal conditions. Where do I make mistake?


April 14, 2013, 21:48 
Newtons method failed to converge in 100 iterations.

#5 
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Join Date: Dec 2012
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Dear a_cucen,
I have also countered this problem"Newtons method failed to converge in 100 iterations ",and have not find a way to deal with it.Could you tell me the reasons that cause this problem.Is it a BC problem or a grid problem?And how can I solve it? Thank you very much!I hope to hear from you soon. 

April 15, 2013, 18:50 

#6 
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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The Newtons method failed to converge message means some material properties could not converge. To debug this you should simplify your problem one thing at a time to isolate what is causing it.


April 16, 2013, 21:57 

#7 
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