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-   -   how to increase "Newton Pressure Iteration Limit" (http://www.cfd-online.com/Forums/cfx/23595-how-increase-newton-pressure-iteration-limit.html)

kus February 1, 2007 05:43

how to increase "Newton Pressure Iteration Limit"
 
I am running a big mesh simulation (nodes: 40300) with two domain interfaces. it is a gas mixture flow and particle tracking only simulation.

In the first iteration, the out file gives the information as below,

+--------------------------------------------------------------------+

| 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. |

+--------------------------------------------------------------------+

According to this message, I am trying to increase the number of iterations for Newtons (Constitutive Relation Iteration Limit and Newton Pressure Iteration Limit) for a material. But I cannot find them in CFX-Pre.

Then I had to search them two in CFX-HELP. The HELP (Reference Guide | ANSYS CFX-Pre CCL Details | CCL Objects |) says as below,

Using the CCL Content Documentation: This document is generated from the CFXPreRules.ccl file in the ANSYS CFX/etc/ directory. It contains a description of all the possible CCL objects and parameters.

But any modifications are prohibited in CFXPreRules.ccl .

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

Looking forward to you reply. Thank you very much in advance.

Georges February 15, 2007 15:50

Re: how to increase "Newton Pressure Iteration Lim
 
If you go into you defenition file editor from post, u can add a paramether to one of your mixtures. The Newton Pressure Iteration Limit can be modified from there.

kus February 15, 2007 19:30

Re: how to increase "Newton Pressure Iteration Lim
 
Dear Georges,

I just cannot find how to add a parameter to my gas mixture in POST. Could you give more details. Thanks a lot.

Ben

Georges February 16, 2007 09:17

Re: how to increase "Newton Pressure Iteration Lim
 
Sure, When you open up Post, go to "tools/edit definition file". Once you have your file open expand the library then select the gas mixture. Once you've done that, click on Edit/Add Paramather. Hope that helps.

kus February 18, 2007 19:06

Re: how to increase "Newton Pressure Iteration Lim
 
Dear Georges,

Thank you for your quick response.

Are you using the CFX5 versions (CFX10.0 and CFX11.0)? I cannot find the library in these versions and thus cannot add parameters to gas mixture. Looking forward to your reply.

Ben

Georges February 28, 2007 16:59

Re: how to increase "Newton Pressure Iteration Lim
 
Hey, I'm using CFX 10. Do you not have the Edit/Add Paramather Option ?

kus February 28, 2007 20:08

Re: how to increase "Newton Pressure Iteration Lim
 
Hi Georges,

I found it. Thanks a lot. May I have you email for future contact?

slurry June 15, 2009 07:09

Quote:

Originally Posted by Georges
;80370
Sure, When you open up Post, go to "tools/edit definition file". Once you have your file open expand the library then select the gas mixture. Once you've done that, click on Edit/Add Paramather. Hope that helps.

Thank you. I have that question. I solved according to what you said.

antonpersson February 15, 2013 07:49

Now in Solver
 
Thank you!

In CFX 14.0 this is done in CFX-Solver Manager. Go to Tools -> Edit CFX Solver File -> Select your material -> Edit -> Add Parameter

BR,
Anton

Magma April 21, 2013 01:54

Newton Iteration slowly converged
 
I have been working out with the tutorial in coal combustion.
I have been receiving the following message:

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.

And I edited the file too, but what is the Constitutive Relation Iteration Limit for temperature and Newton Pressure Iteration Limit for pressure or what does that mean.

The next problem is the solver runs and stalls after 25-30 iterations with this message in serial mode and does not run in parallel mode. I have set expert parameters for memory allocation too.
What might be the problem? Help would be appreciated.


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