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-   -   What is the meaning.. ??? (https://www.cfd-online.com/Forums/fluent/30737-what-meaning.html)

 lopez January 1, 2003 15:21

What is the meaning.. ???

Hi all,

Happy New Year to Fluent-Users!!!

What is the meaning of the following Message:- "Turbulent Viscosity limited to viscosity ratio of 1.0e+5."

What is the implication? What action is to be taken in this case?

With regards,

Lopez

 Jinbok Yoo January 2, 2003 05:51

Re: What is the meaning.. ???

1.0e+5 is set on solve/limit panel(you can change the limit values), and when the values of some cells exceed the limit value in the iteration, Fluent prints the message and replaces the exceeded values with the limit value.

Jinbok

 Alamgir January 3, 2003 05:14

Re: What is the meaning.. ???

In that case usually u need to under reluxed the control criterion, decrease the URF and keep going.

Alamgir

 lopez January 4, 2003 04:12

Re: What is the meaning.. ???

Dear Alamgir,

Thanx for reply. What is the implication of this? what does it physically mean? How much the URF to be decreased, Please give some guidelines for this.

Lopez

 Alamgir January 5, 2003 20:52

Re: What is the meaning.. ???

Ref: NUMERICAL HEAT TRANSFER AND FLUID FLOW-By S V Patankar. In this book u will have clear idea about ur 1st 2 questions. If u under relax that means u r taking that much quantiy from the past iteration. There is no hard and fast rule how much u need to decrease but every time decrease it by 1/2 and keep going upto 0.01. Remind if URF less u need more iterations to have converged results.

Alamgir

 bitak September 11, 2009 10:01

Hi.
I work on project about subsonic ejector like you.
My solve is :air - couple - axisymetric - k-e rng - pressure inlet and outlet ideal gas - my presure inlet are 150 ,250 ,350 ,450 Kpa and out let is atmosphere.
unfortunately my solve is divergence!!!!!!!!!
really I need to your help.
I change k-e to k-omega and pressure inlet to mass flow but devegence again.I know i have a shoke and so reverse flow in fluent.

 Mortie November 2, 2016 04:48

Quote:
 Originally Posted by bitak (Post 229265) Hi. I work on project about subsonic ejector like you. My solve is :air - couple - axisymetric - k-e rng - pressure inlet and outlet ideal gas - my presure inlet are 150 ,250 ,350 ,450 Kpa and out let is atmosphere. unfortunately my solve is divergence!!!!!!!!! really I need to your help. I change k-e to k-omega and pressure inlet to mass flow but devegence again.I know i have a shoke and so reverse flow in fluent.
use density based k-epsilon , lower your URF and Currant number in the case of divergence, and check your mesh quality

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